S58 Catless Downpipes: Power, Sound, and Fitment for the M3, M4 & M2

A 2022 G82 M4 Competition leaves the factory with 503 hp, two turbos, and two catalytic converters sitting directly behind the turbine outlets. Those two cats are the biggest restriction between the turbos and the tailpipes, which is why S58 catless downpipes are the first hardware most G80 M3, G82 M4 and G87 M2 owners buy before a Stage 2 tune.

This article decides whether our own 3 inch S58 catless downpipes are the right set for your car, what the whole job costs once the tune and DME unlock are counted, how the install goes on rear drive and xDrive cars, and when a catted set or the stock pipes are the smarter choice. We build and sell these pipes, so we have a bias; the limitations are stated up front.

Prices and fitment come from our product page and from Active Autowerke and Evolution Racewerks maker pages. Prices vary by dealer. Owner experiences come from G80 and G87 Bimmerpost threads.

Shop the OneFastShop S58 Catless Downpipes

The Short Answer

• Gain: 30 to 50 hp over stock with a supporting tune, per our product page. On the stock map they set a P0420 or P0430 code.
• Fitment: 2021 to 2026 G80 M3, G82 M4 and G83, 2023 to 2026 G87 M2, incl. Competition and xDrive. Not the F97 X3 M or F98 X4 M.
• Price: $290 plus two $19.99 gaskets; the tune and DME unlock add $1,100 to $2,200.
• Legal: off road and competition use only. Inspected daily drivers want a catted set.

At a Glance

What S58 Catless Downpipes Actually Change

S58 catless downpipes replace the two factory downpipes, each carrying a ceramic catalytic converter inches from a 3.5 inch V-band turbine flange, with two open 3 inch stainless pipes. Backpressure that close to a turbine works directly against it; cut it and the turbos reach target boost sooner and a tuner can ask for more without pushing exhaust temperatures as hard.

The pipes add nothing on their own; they remove a restriction so a tune can use the room. Our product page rates them at 30 to 50 hp over stock with a supporting tune, more on upgraded turbo builds, and gives a range because the result depends on fuel, tune and the rest of the hardware. Owners do report sharper throttle response even on the stock map.

One limitation up front: on the stock map, the DME still expects to see a working cat through the rear oxygen sensors. Run these pipes without a tune and you will get a catalyst efficiency code, P0420 or P0430, and a check engine light. Plan the tune with the pipes, not after; our S58 Stage 1 vs Stage 2 guide covers what the tune itself does.

Catless vs Catted vs OEM: Which S58 Downpipe Should You Buy

Catless pipes win on price and flow, catted pipes win on smell, rasp and check engine lights, and the OEM pipes win if your car visits a dealer or a smog station every year. Prices below are each maker's own list price.

AMS also sells a GESI based catted set; we did not confirm its current price. If you drive the car to work in a state that inspects, the Active Autowerke or Evolution Racewerks catted sets are the better buy even at six to ten times our price. On a tuned car headed for Stage 2, the catless set does the same job for less, and even 200 cell sets sometimes need spacers or a tune to stay code free.

Fitment by Chassis and Year

The OneFastShop S58 downpipes fit every US market G8x M car from 2021 to 2026, rear drive or xDrive, and nothing else; our fitment data includes the M3 CS, M4 CS and M4 CSL. Stock outputs are crank figures, so a wheel dyno reads lower before any mod.

The F97 X3 M and F98 X4 M share the S58 but route the downpipes differently; Evolution Racewerks and Active Autowerke each sell a separate set for them and we do not list one, so email us with your build details rather than ordering this set.

What the Whole Job Costs

The pipes are the cheapest line on the invoice; the DME unlock and tune cost four to seven times more. Every G8x has a locked Bosch DME that bootmod3 and MHD both need bench unlocked first, as our bootmod3 vs MHD comparison explains.

That total is why a cheaper pipe makes sense here: the $800 saved against a US made catless set buys no extra horsepower, but it covers most of the DME unlock you cannot skip. We are an authorized dealer for every brand we carry, and in stock hardware ships fast. The downpipes ship free to the lower 48 states with no minimum, per the product listing, and we ship worldwide with shipping calculated at checkout.

Sound: Louder, Raspier, and What Drone Really Comes From

S58 catless downpipes make the car noticeably louder, bring out turbo and wastegate noise the cats hid, and on most cars add some rasp between 2,000 and 4,000 rpm at part throttle. The hard edge under full throttle is what people buy them for; the half throttle rasp is what a few come to regret.

The rasp reports are consistent on Bimmerpost: a G80 M3 owner with resonated catless downpipes and a resonated single mid pipe still found an E46 M3 style rasp at 3,000 to 4,000 rpm at half throttle, and two vendors agreed only a catted set or a resonated mid pipe really tames it. Another owner with catless pipes and the stock mid section called that combination close to perfect. Your ears decide.

Drone is different and comes from the rear of the system. An X3 M Competition owner with a single mid pipe and catless downpipes reported zero drone, and a G80 M3 owner with a droning aftermarket axle back was told, correctly, that downpipes would only make it louder. Catless cars also smell; a G82 owner said keeping the secondary cats in the stock mid section meant no smell at all. On European and other non US cars, the OPF particulate filter sits behind the downpipes in its own section; these pipes leave it in place, and removing it is a separate pipe plus coding.

Installing S58 Downpipes: Two Pipes, Four O2 Sensors, One Tight Clamp

The install takes an experienced hand about 2.5 hours on a lift and a first timer on jack stands a full weekend, and xDrive cars are harder because the front driveshaft and front axle housing crowd the short downpipe. It is a bolt-on with no cutting, but it is not an oil change.

The sequence, as laid out in the long Bimmerpost G80 DIY thread: disconnect the battery in the trunk, because the starter sits close to where you will be prying. Pull the engine cover and strut brace and unplug the four oxygen sensor connectors, two of which live up top. Underneath, remove the belly pans and center cross brace, then unbolt the mid pipe and support it on a jack.

At the turbos, remove each V-band clamp bolt completely and pry the clamp off its 3.5 inch flange; it stays stuck to the pipe after the bolt is out. Lift each pipe out with its sensors fitted, swap the sensors on the bench with an O2 socket, and fit the long pipe first with a fresh gasket. Torque clamps, flange bolts and sensors to BMW TIS values; the turbo clamp spec is lower than most people expect, so look it up rather than leaning on the wrench.

The spot that catches people is the bolt joining the short downpipe to the mid pipe; a 2024 M3 Competition xDrive owner fought it for days until a crow's foot on a long extension with a flex head ratchet solved it. If you are weighing whether to do the mid section at the same time, our downpipe vs cat-back guide settles that.

What Owners Actually Say

G8x owners on Bimmerpost describe catless downpipes as the mod that made the car sound like an M car, and the mod that introduced them to catalyst codes, exhaust smell and a clamp that would not come off. These are paraphrased; the forum is named, the owners are not.

The weekend that became several days. A 2021 G82 M4 owner with 11,000 miles and self described novice to intermediate skills installed catless downpipes alone on a low profile jack and flat top stands. It took several days. His notes afterward: label every fastener because there are dozens, soak the exhaust bolts in penetrating oil first, pry each V-band clamp fully off, keep the rubber hanger flanges from the old pipes because the new ones need them, and unplug the positive battery relay connections to reach the oxygen sensor hiding behind them. The car ran, and he wrote it all up so the next person would not repeat his week.

• Catless on the stock tune, then second thoughts. A 2024 G87 M2 owner ran catless downpipes with a cat-back on the stock map. The sound was great; the garage smell and the catalyst codes were not, and he decided his warranty mattered more. His plan was to refit the stock cats a thousand miles before service so the permanent codes could clear, then consider a GESI catted set.
• Rasp despite the resonators. A G80 M3 owner paired resonated catless downpipes with a resonated mid pipe expecting a clean tone and got a 3,000 to 4,000 rpm rasp at part throttle. He decided to swap to a 200 cell catted set.
• Spacers are not a tune. An M4 Competition xDrive owner on the later LCI software tried mini cat spacers to keep the light off without a tune. The car threw P0133 and P0145 immediately with a rough idle, and he ended up sending the DME out for an unlock anyway.

Legal and Emissions

This part is sold for off road and competition use only. Removing or defeating a catalytic converter on a vehicle driven on public roads violates the Clean Air Act, and many states inspect for it. Check your state and local laws before buying.

In practice, catless pipes fail both a visual check for the converters and an OBD readiness check, because a tune that turns the rear sensors off leaves the catalyst monitor incomplete. Catted sets are not a loophole either: we could not find a CARB Executive Order for any aftermarket S58 downpipe, so none of them, ours included, can be sold as emissions legal in California or the states that follow its rules. Active Autowerke states its GESI cats are EPA registered and 49 state compliant; that is the maker's claim, not a vehicle specific verification.

Returns follow our refund policy: unused competition parts can come back within 30 days with an 8 percent restocking fee, and discovering that the part is not legal on your street is not a return reason. Defects are covered for 1 year under our house brand warranty.

Mistakes We See

• Installing the pipes, then shopping for a tune. Every G8x needs the DME bench unlocked, one to three weeks with the DME out of the car. Order the unlock first, or accept a check engine light while you wait.
• Reusing the crushed turbo gaskets. The 18307553601 gasket is a single use crush ring; one owner's old ones came off flat and a dealer wanted $49 each in a hurry. Order two with the pipes.
• Driving around the code with spacers. Mini cats and O2 spacers work for some owners and set rough idle codes for others, and they feed the DME data about a cat that is not there. A tune with the rear sensors off is the clean fix.
• Skipping the battery disconnect. The starter sits where the pry bar goes on the V-band clamp, and the Bimmerpost walkthrough warns you can short the electrical system on it.

Who This Is For (and Who Should Skip It)

This set is for the G8x owner who has already decided on a Stage 2 tune, drives a car that will never see a smog station or a dealer warranty claim, and would rather put the money saved on pipes toward the DME unlock.

Skip it if the car is leased, under factory warranty and dealer serviced, registered in California or another inspection state, or if rasp and exhaust smell would bother you in a daily driver. Those owners should look at a catted set from Active Autowerke or Evolution Racewerks, or do a mid pipe and leave the downpipes stock. The G87 owner above was planning to buy downpipes twice to learn this.

If It Were Our Car

On a G80 M3 or G82 M4 bound for Stage 2 and not subject to inspection, we would install these pipes with two fresh gaskets, send the DME for unlock the same week, and flash a Stage 2 map. That is the combination our 30 to 50 hp figure is written for.

On a G87 M2, same answer with one caution: the M2 is the one most often bought as a daily, and it carries the same smell and rasp. On an xDrive car we would pay a shop the $250 to $400 rather than fight the short pipe on jack stands. On any car that must pass an OBD inspection, we would not sell you these; a catted set or the stock pipes is the honest answer.

What They Pair With

The pipes are step one of a Stage 2 build and the rest of the list is short. Start with two 3.5 inch turbo to downpipe gaskets, one per turbo, in the same order. Add a tune on whichever platform your tuner uses. Then decide on the mid section: the AWE non resonated mid pipe for the G8x is the common next step, and the rest of the G8x systems, from Akrapovic slip ons to AWE SwitchPath, live in our exhaust and muffler collection.

More power means more heat, and our S58 cooling guide covers what to add once the tune is on. For other engines, we cover catless downpipes for the S55 F80 M3, F82 M4 and F87 M2 and the B58 M240i, M340i and Supra; every set we make is in the OneFastShop parts collection and our full downpipe collection.

Get the S58 Catless Downpipes and Gaskets

The Bottom Line

S58 catless downpipes are the hardware that makes a Stage 2 tune worth flashing on a G80 M3, G82 M4 or G87 M2, and our 3 inch set does that job for $290 against $1,095 to $2,999 for the alternatives. The 30 to 50 hp figure needs the tune, and the tune needs a DME unlock that costs more than the pipes, so budget the whole job before you order. Expect a louder car with some part throttle rasp, a smell the cats used to catch, and a code on the stock map. If the car is inspected, leased or dealer serviced, buy a catted set or leave the stock pipes alone. If it is a tuned car that lives off the inspection grid, order the pipes, two gaskets and the unlock together.

Frequently Asked Questions

How much power do S58 catless downpipes add?

Our product page rates the OneFastShop S58 catless downpipes at 30 to 50 hp over stock with a supporting tune, more on upgraded turbo builds. On the stock map the gain is small and the car sets a catalyst code.

Do I need a tune to run S58 catless downpipes?

Yes. Without a tune that turns off the rear oxygen sensors, the DME sets P0420 or P0430 and a check engine light. Every 2021 and newer G8x also needs a DME bench unlock, about $800 to $1,600 in the US, before bootmod3 or MHD can flash it.

Are S58 catless downpipes street legal?

No. This part is sold for off road and competition use only. Removing or defeating a catalytic converter on a vehicle driven on public roads violates the Clean Air Act, and many states inspect for it. Check your state and local laws before buying.

Do these downpipes fit the X3 M and X4 M?

No. The F97 X3 M and F98 X4 M use the same S58 but a different downpipe set, which we do not list. This set fits the 2021 to 2026 G80 M3, G82 M4 and G83 M4 Convertible and the 2023 to 2026 G87 M2 only.

How hard is the install on an xDrive M3 or M4?

Harder than on a rear drive car, because the front driveshaft and front axle housing crowd the short downpipe and the bolt joining it to the mid pipe. Owners report $250 to $400 for a shop install, which we would pay on an xDrive car.

Will catless downpipes make my S58 raspy or droney?

Some rasp at part throttle between 2,000 and 4,000 rpm is common with any catless pipe; a resonated mid pipe reduces it. Drone comes from the rear section and muffler valves, not the downpipes, and pipes only make existing drone louder.

What gaskets do I need for S58 downpipes?

Two 3.5 inch turbo to downpipe gaskets, one per turbo, matching BMW part 18307553601. They are single use crush gaskets, so replace them whenever the pipes come off. We sell them individually for $19.99.