FL5 / DE5 Downpipe Guide: Catted vs Sports Cat vs De-Cat, CEL Risk, and the Best Options Right Now
Sound, smell, heat, and check engine lights. A downpipe changes all of it. Here's what actually matters for daily drivers, tuned cars, and track builds.
The Honda Civic Type R FL5 and Acura Integra Type S DE5 both respond well to better exhaust flow, but a downpipe is one of the fastest ways to change sound, smell, heat, and your odds of seeing a check engine light. This guide focuses on the options FL5 and DE5 owners actually cross-shop, with special attention to daily drivability, catalyst quality, and fitment reality.
DE5 buyer note: Not every listing that fits the FL5 is explicitly sold for the DE5. Where a product is clearly listed for FL5/DE5, I say that. If a brand only lists FL5 or FK8/FL5, treat it as an FL5-reference option until the seller confirms exact DE5 fitment.
Emissions laws vary by state and country. "Race cat," "sports cat," "de-cat," and "cat-delete" parts may be sold for off-road or motorsport use only. Always confirm local legality before modifying emissions equipment.
Legal disclaimer: SBX Performance provides product information for educational purposes only. Laws and emissions requirements vary by jurisdiction and may change over time. It is the purchaser's responsibility to confirm legality and emissions compliance for their vehicle and location prior to purchase or installation. SBX Performance does not assume liability for inspection failure, fines, penalties, or non-compliance related to product use.
- FL5 focused
- DE5 buyer notes included
- Catted vs De-Cat
- Best-by-goal picks
- CEL reality
Parts covered in this guide
- SBX Performance GESI Catted Downpipe – FL5 / DE5 / FK8
- SBX x PTP Downpipe Blanket
- RV6 High Temp Catted Downpipe – FK8 / FL5 / DE5
- Two Step Performance High Efficiency Downpipe – FK8 / FL5 / DE5
- MST Performance 300-Cell Catted Downpipe – Civic Type R FL5
- PLM Power Driven Catted Downpipe – FL5 Civic Type R / DE5 Type S
- Best daily-driver direction: a quality high-flow catted downpipe with good heat management and realistic CEL expectations.
- Best current DE5-friendly buying strategy: prioritize listings that explicitly mention DE5 or are already known to be sold as FL5/DE5 parts.
- Most aggressive sound and smell: de-cat / catless setups.
- Lowest headache on a street car: larger, higher-quality catalyst designs usually beat tiny "race cat" solutions.
- Biggest mistake buyers make: assuming every FL5 downpipe is automatically a perfect DE5 fit without checking the listing.
On paper, the FL5 and DE5 are very close. In the real world, buyers should still care about listed fitment, turbo outlet design, front-pipe connection style, sensor placement, and whether a brand has actually validated the part on the chassis they are selling it for.
If a product is marketed as FL5/DE5, that is the safest path for DE5 owners. If it is only listed as FL5 or FK8/FL5, it may still be relevant, but it should be treated as a comparison point until the seller confirms it for the DE5.
If you want the lowest-friction path today, start by looking hardest at the options that are already sold as FL5/DE5 or FK8/FL5/DE5, then work outward from there.
Daily Catted
Sound: Stronger than stock, easier to live with long-term.
Smell: Usually much lower than catless once warm.
CEL risk: Lower when catalyst quality and placement are good.
Best for: street cars, commuting, long-term ownership.
Sports Cat / Race Cat
Sound: Typically louder and sharper than daily catted setups.
Flow: Generally better than a denser OEM-style catalyst.
CEL risk: Middle ground, very dependent on catalyst quality and ECU behavior.
Best for: tuned cars that still want some catalyst in place.
De-Cat / Catless
Sound: The loudest and most raw option.
Smell: Highest odor, especially cold start and stop-and-go.
CEL risk: Highest.
Best for: track-first, off-road, or dedicated aggressive builds.
Heat Still Matters
The FL5/DE5 engine bay is not where you want to get lazy with thermal control. Whether catted or de-cat, plan for ceramic coating, blankets, hard lagging, or OEM heat shield retention if the design supports it.
These are not "absolute rankings." They are the most practical way I'd separate the current options if the goal is to help a real FL5 or DE5 owner buy the right part the first time.
Best Daily-Driver Direction
- SBX Performance 3.5" GESI Catted: our pick for most FL5 and DE5 owners, and it's not close. 3.5" primary, a big 4.5" GESI GEN2 UHO #85200 catalyst rated to 850 HP, 3" outlet, optional full titanium hardware, and true FL5/DE5 fitment. This is our part, built from a blank sheet around daily drivability, heat management, and the real install headaches we got tired of seeing. You get aggressive-setup flow with a cat that keeps it civil and CEL-free on a proper tune.
- TSP High Efficiency: big 5" OD / 400 CPSI GESI G-Sport catalyst, daily-minded, no tune and no CEL on most cars. It's the continuation of the proven PRL design and one of the better high-flow cats you can buy. Just order ahead, lead times can run long.
- MST 300-Cell Catted: very daily-oriented positioning, CEL-free focus.
- 27WON Catted Downpipe: 200-cell metallic foil cat, retains OEM heat shields, CEL-free, strong community reviews for fitment and build quality.
- RV6 High Temp Catted: 300-cell high-temp metallic cat, OEM heat shield provisions, strong all-around option. Needs tune for best results.
Best DE5-Minded Shopping Path
- SBX Performance 3.5" GESI Catted: designed from the start as a true FL5/DE5 solution.
- RV6 High Temp Catted: already sold as FK8/FL5/DE5.
- PLM Power Driven Catted: budget option sold as FL5/DE5.
Best Premium Catted Options
- HKS Metal Catalyzer (new FL5 downpipe): HKS's new FL5-specific piece, 150-cell metal core, roughly 51% less restriction than stock, mirror-finish SUS304, heat shield included. Sits at the top of the price ladder.
- Milltek with HJS High Flow Sports Cat: 3" with HJS 200-cell, premium UK option.
- Milltek with Twin 200 Cell HJS Cat: high-end HJS-based solution, availability can depend on HJS supply.
Best Aggressive / Track-First Direction
- Dream Automotive De-Cat: 3.5" tapering to 3", tangential outlet, hard lagging and Zircotec coating options.
- Milltek Large-Bore De-Cat: simple, recognized catless option.
- Scorpion DE-CAT: FL5-specific, 3.5" pipe, budget-friendly aggressive path.
- Cobra Sport De-Cat: 4" reducing to 3", handmade UK, removes PPF.
Best "Both Worlds" Option (Budget)
- Axion Industries 2N1 Downpipe: the budget, entry-tier way into a swappable catted-or-catless downpipe. The center section swaps between the two, so the appeal is price and flexibility. Just know the V-band design trades some long-term robustness for that, so treat it as the value pick rather than a lifetime part.
This is the one we build, and the one we'd bolt to our own cars. So I'm going to be straight about exactly what it is and why it's the downpipe most FL5 and DE5 owners should be buying.
- Primary section: 3.5" directly off the turbo, which is where the most heat and restriction lives, and where diameter matters most for spool and turbo efficiency.
- Catalyst: 4.5" GESI GEN2 Advanced G-Sport UHO #85200, rated up to 850 HP. Not an entry-level core, not vague "GESI style" language. We tell you exactly what catalyst is in the pipe.
- Outlet: 3" to match the factory front pipe location cleanly. The larger section is kept where it delivers the greatest benefit, then reduced appropriately downstream.
- Hardware: Complete Install Kit includes JD Customs titanium studs (turbo flange, burnt finish) and titanium bolts (front pipe flange, burnt finish). No mixed stainless. No zinc bolts. No chasing old corroded hardware during install.
- Fitment: Honda Civic Type R FL5 (2023+) and Acura Integra Type S DE5 (2024+). This was designed for these cars from the start, not adapted from something else.
- Includes: O2 sensor extension harness, lower gasket (3" three-bolt, high temp), heat shield hardware/spacer kit.
Pricing: Downpipe Only: $1,349 (MAP $1,499). Complete Install Kit: $1,399 (MAP $1,599, includes full titanium hardware at both flanges). Optional OEM Honda turbocharger gasket add-on: +$89.99.
The turbo flange and front pipe flange are the two highest-heat connection points in the system. Zinc hardware rusts. Stainless can gall or seize. Titanium resists corrosion, handles heat cycling better, and comes apart cleaner later when the car needs service. Most customers should choose the Complete Kit.
Bottom line: biggest named catalyst in the group, exact specs published, titanium hardware, and true FL5/DE5 fitment for well under the premium JDM options. If you want one downpipe that flows hard, stays clean, and just works on a daily, this is it.
Not all "GESI cats" are the same core. The G-Sport catalyst is built on a spiral-wound (S-Wound) metallic matrix, and the number of active catalyst cores wound into that matrix is what separates the three designs. More cores means more catalytic surface area and flow capacity, which is why the multi-core versions get used on larger-diameter, higher-horsepower builds.
Spiral-Matrix (One Core)
A single catalyst core wound into the spiral metallic matrix.
Clean, efficient, and the right amount of catalyst for most single-turbo street cars like the FL5 and DE5.
Best for: daily and street power levels.
S-Matrix (Two Cores)
Two cores in the matrix for more catalytic surface area and flow headroom.
Steps capacity up for bigger builds pushing more exhaust volume.
Best for: higher-output, larger-diameter setups.
SM-Matrix (Three Cores)
Three cores for the most catalytic surface of the group.
Built for the biggest power and flow targets where a single core would choke.
Best for: high-HP and big-turbo builds.
What's in Our Downpipe
Our SBX FL5/DE5 pipe runs the GESI GEN2 Advanced G-Sport UHO #85200, a 4.5" high-output core sized so a single core flows plenty for these cars while staying clean and CEL-free on a tune.
RV6 High Temp Catted Downpipe
Fitment: FK8 / FL5 / DE5
- 300-cell high-temp metallic cat, 304 stainless, cast transitions, OEM heat shield mounting points retained.
- 24-month warranty on castings and welding (no warranty on catalytic converters).
- Ceramic coating option available (+7 to 14 business days processing).
- Who it fits best: Buyers who want one premium answer instead of gambling. One of the few options already sold across FK8/FL5/DE5.
- Note: Tune recommended for best results. Community reports CEL P1039 on some cars without a tune.
27WON Catted Downpipe
Fitment: FK8 / FL5 / DE5 / Accord 2.0T
- 200-cell metallic foil catalytic converter, T304 stainless steel construction, TIG welded.
- Designed to retain all OEM heat shield pick-up points.
- Dyno-proven: +10 WHP and +28 lb-ft average over stock (best run: +33 lb-ft) on Dynapack.
- No CEL reported by owners. Strong community reviews for build quality and fitment.
- Available as standalone or with $49.99 discount when purchased with 27WON catback as a full turboback system.
- Who it fits best: Owners who want a proven, CEL-free catted option with excellent build quality and the option to pair it with a complete 27WON exhaust system.
TSP High Efficiency Downpipe
Fitment: FK8 / FL5 / DE5 / Accord 2.0T / RDX / TLX
- 304 stainless investment-cast ends, CNC pocketed for smooth transitions.
- 5.00" OD 400 CPSI GESI G-Sport catalytic converter, marketed as 48-state EPA approved.
- This is the continuation of the proven PRL downpipe design. TSP picked up production after PRL stepped away from downpipe manufacturing over California emissions concerns.
- No tune required, no CEL on most installs.
- Catalyst quality: The GESI G-Sport core here is a genuinely great high-flow catalyst. It flows hard, stays clean on emissions, and TSP backs it as a real 48-state daily option. If you want a big-cat daily setup and the SBX GESI GEN2 isn't in the cards, this is a strong choice, and TSP is a shop we're happy to point people to.
- Good to know: A few owners have noted heat shield bolt holes needing a little massaging on some units. Minor, and not universal.
- Lead times: Can run long, multiple weeks to months depending on the batch. Order ahead and you're set.
MST 300-Cell Catted Downpipe
Fitment: FL5
- Very daily-friendly positioning, CEL-free focus, large catalyst design.
- 304 stainless, hand TIG welded, high-flow cat rated for 500 HP.
- Includes install hardware + O2 sensor extension.
- Note: Some community reports of heat shield bolt hole alignment issues, minor but worth knowing.
PLM Power Driven Catted
Fitment: FL5 / DE5
- Budget catted option with FL5/DE5 listing support.
- Attractive pricing, but budget parts always deserve careful inspection before install.
- Who it fits best: Cost-conscious buyers who still want catted + DE5 listing support.
Axion Industries 2N1 Downpipe (Budget Tier)
Fitment: FK8 / FL5 / DE5
- Swappable center section, so you get catted AND catless in one downpipe.
- The draw here is price and flexibility. It's the cheap-tier entry point if you want both configs without buying two pipes, and it's listed for FK8/FL5/DE5.
- The tradeoff: V-bands in a high-heat spot can seize after enough heat cycles, and every clamp joint is one more place a leak can start. That's the price you pay for a budget swappable design.
- My honest take: If you want the most affordable way into a do-it-all downpipe and you're okay with a little more maintenance down the road, Axion gets you there. If you know you'll leave it alone, spend up a tier for a single-piece pipe. Eyes open, it's the value pick.
Cobra Sport HN29 Sports Cat / De-Cat
Fitment: FL5
- 4" / 101.6mm reducing to 3" / 76.2mm pipework.
- Sports cat version: 4.5" 200-cell high-flow catalyst.
- Removes the PPF, tuning required to cancel EML on PPF-equipped vehicles.
- Handmade to order in the UK, typically 7 to 10 working days.
Scorpion Sports CAT / DE-CAT Downpipe
Fitment: FL5
- 89.9mm / 3.5" pipe diameter. Available in sports cat or de-cat configurations.
- Fits OEM or Scorpion exhaust systems.
- Stage 2 ECU remap recommended. EML may be activated.
- Good FL5-specific option without ultra-premium pricing.
HKS Metal Catalyzer Catted Downpipe (New for FL5)
Fitment: FL5-specific (part #33005-AH006, K20C, 2022/09+)
- HKS's new FL5-specific downpipe. It swaps the restrictive factory ceramic cat (a 600 + 400 cell setup) for a low-density 150-cell metal core, cutting exhaust restriction by roughly 51% versus stock while keeping catalytic function.
- SUS304 stainless, TIG welded and buffed to a mirror finish, with a lost-wax cast, vehicle-specific outlet that smooths flow right off the turbine.
- 93mm inlet tapering to a 74.7mm outlet, purpose-designed heat shield included.
- Cuts secondary exhaust pressure by up to about 28% on its own, closer to 40% paired with an HKS LEGAMAX cat-back.
- Heads up: HKS's exhaust gas certification is for the Japanese market, so confirm your local regs before street use. This sits at the top of the price ladder, it's a premium JDM piece and priced like one.
- Who it fits best: FL5 owners who want the HKS name, JDM engineering, and a mirror-finish part, and aren't shopping on price.
Milltek HJS High Flow Sports Cat
Fitment: FK8 / FL5
- 3.00" / 76.2mm downpipe with HJS 200-cell high-flow cat.
- Milltek recommends pairing with Milltek exhaust components rather than mixing systems.
- Often 1 to 3 day dispatch when in stock.
Milltek Twin 200 Cell HJS Cat
Fitment: FK8 / FL5
- Higher-end HJS-based catted solution. Often listed at 5 to 15 day dispatch.
- Availability can depend on HJS catalyst supply chain.
Dream Automotive De-Cat
Fitment: FK8 / FL5
- Lightweight T304 stainless. Tangential turbo outlet, 3.5" bend tapered to 3" outlet.
- Available without coating, with hard lagging, or with black Zircotec ceramic coating.
- One of the better de-cat choices for buyers who actually care about heat control.
- Motorsport use only.
Milltek Large-Bore De-Cat
Fitment: FK8 / FL5
- Large-bore de-cat design. Track/motorsport use only, Stage 2 remap required.
- Often shown as 1 to 3 day dispatch. Simple and straightforward catless option.
| Option | Fitment | Type | Bias | Key Detail |
|---|---|---|---|---|
| SBX Performance 3.5" GESI | FL5 / DE5 | 3.5"→4.5" GESI GEN2 UHO→3" | OEM+ street / performance | 850 HP rated cat, titanium hardware, designed for FL5/DE5 from the start |
| RV6 High Temp Catted | FK8 / FL5 / DE5 | 300-cell high-temp metallic cat | Best all-around | Premium construction, OEM heat shields retained, tune recommended |
| 27WON Catted | FK8 / FL5 / DE5 / Accord | 200-cell metallic foil cat | CEL-free daily | OEM heat shields, +10 WHP / +28 WTQ avg, no CEL |
| TSP High Efficiency | FK8 / FL5 / DE5 / Accord | 5" OD 400 CPSI GESI G-Sport | Daily-minded | Proven PRL-derived design, 48-state EPA marketed, no tune / no CEL; order ahead for lead times |
| MST 300-Cell Catted | FL5 | 300-cell catted | Daily-driver bias | CEL-free focus, daily-oriented positioning |
| PLM Power Driven Catted | FL5 / DE5 | High-flow catted | Budget street | Price and DE5 listing are the draw |
| Axion Industries 2N1 | FK8 / FL5 / DE5 | Catted + catless (V-band swap) | Budget / value | Cheapest way into a swappable pipe; V-bands can seize over time, more leak points |
| Cobra Sport HN29 | FL5 | Sports cat or de-cat | Motorsport-leaning | 4"→3", handmade UK, removes PPF, tuning required |
| Scorpion Sports CAT / DE-CAT | FL5 | 3.5" sports cat or de-cat | Street / aggressive | FL5-specific, affordable, Stage 2 remap recommended |
| HKS Metal Catalyzer | FL5 (new) | 150-cell metal core, 93→74.7mm | Premium JDM | New FL5-specific pipe, ~51% less restriction vs stock, mirror-finish SUS304, top price tier |
| Milltek HJS Sports Cat | FK8 / FL5 | 3" with HJS 200-cell cat | Premium street | Best matched with Milltek exhaust components |
| Milltek Twin 200 Cell HJS | FK8 / FL5 | Twin 200-cell HJS | High-end catted | Premium HJS, availability varies with supply |
| Dream Automotive De-Cat | FK8 / FL5 | 3.5"→3" de-cat | Track / heat-managed | Tangential outlet, hard lagging + Zircotec options |
| Milltek Large-Bore De-Cat | FK8 / FL5 | Large-bore de-cat | Track-first | Simple motorsport-style catless option |
- Turbo hardware matters: Heat-cycled turbo fasteners can turn a "quick install" into a time sink. Plan for penetrant, patience, and replacement hardware, or just get a kit with titanium hardware from the start.
- Heat management is not optional on harder-driven cars: Blankets, coatings, and OEM shield retention matter more than most people think.
- Do not assume DE5 fitment from an FL5-only title: Confirm it first.
- Sports-cat and de-cat setups frequently want a tune: Especially if you remove major restrictions or emissions equipment.
- Think about the whole exhaust path: Downpipe, front pipe, cat-back, and tune all change the final result together.
- Stock-tune reality: Most dyno charts online are on tuned cars. On a stock ECU, peak gains can be smaller than expected. Once calibration is optimized, a downpipe becomes a stronger "multiplier."
If your car is a daily-driven FL5 or DE5, get a quality catted setup with good heat control and real fitment support. Our SBX 3.5" GESI is where we'd start every time, it's the most complete daily package we know of for these cars. The RV6 High Temp, 27WON, and TSP High Efficiency are all strong paths too, depending on your budget and priorities.
If your goal is a more aggressive car, the sports-cat options from Cobra and Scorpion are the middle ground, and the HKS Metal Catalyzer is there if you want a premium JDM catted pipe. If you know you want the loudest, rawest, highest-flow result and accept the tradeoffs, Dream Automotive and Milltek de-cat options are where that conversation starts.
For DE5 owners specifically, the safest shopping path today is still to prioritize products already listed for DE5. SBX Performance, RV6, PLM, and Axion Industries all have you covered.
- SBX Performance FL5/DE5 3.5" GESI Catted Downpipe: $1,349 / $1,399 Complete
- RV6 High Temp Catted Downpipe (FK8 / FL5 / DE5)
- MST 300-Cell Catted Downpipe (FL5)
- TSP High Efficiency Downpipe (FK8 / FL5 / DE5)
- MAPerformance Downpipe (FL5)
- PLM Power Driven Catted Downpipe (FL5 / DE5)
- Milltek Cast Downpipe with HJS Hi-Flow Sports Cat
- Milltek Cast Downpipe with Race Cat
- Milltek Large-Bore Downpipe + De-Cat
Need Help Choosing?
We've installed, heard, and tuned around most of these downpipes. Hit us up and we'll help you pick the right one for your goals, fuel setup, and daily-driving reality.