E92 M3 Replacement Exhaust Needed

[benaldo]

Just had a call from the garage to say there are a couple of cracks in the exhaust and now also confirmed that both cats are cracked too so probably need a new exhaust system .

The current one on there was the modded OEM which I've had on it since I bought it about 5 yrs ago.

I haven't really experienced the standard exhaust and wouldn't want to get anything louder than I had. From some google searches, prices seem to be all over the place. How much do you think I am looking at and what other options are out there?

[survivalist]

I think the x-pipe / cats themselves go for about £400 quid - people who have them removed and replaced with test pipes seem to sell them to breakers for about that. Back box around £250 probably. So in total probably looking at £800-1000 for the full system.

When I bought my M3 from BMW they said that the back boxes new from BMW were over £1000 so used on the forums and Facebook groups is probably your best option. There's a guy on Facebook who breaks them all the time, will try and dig up his name.

Or go nuts and fit the full Akrapovic titanium system

[benaldo]

Think the full akrapovic system might be a bit noisy and hurt the wallet .

It's currently at an independent BMW garage that I've used for years but i was thinking around £1k would be the ball park !

[benaldo]

Has anyone got any experience of cobra exhausts ? They appear to have a sports cat front system for around £1400. I accept that it will be louder and the sound clips don’t sound too bad but some PH knowledge would be good!

Sound / drone / etc.

[survivalist]

benaldo said:

Has anyone got any experience of cobra exhausts ? They appear to have a sports cat front system for around £1400. I accept that it will be louder and the sound clips don’t sound too bad but some PH knowledge would be good!

Sound / drone / etc.

I had the cat back cobra on mine. It’s considerably louder than the standard exhaust. You said you OEM box is modded, do you know what ‘level’ of mod it had? I’d say that the cobra exhaust is close to a 4-pipe mod on OEM, which is petty much the same as a backbox delete.

My cobra system was probably slightly quieter than a 4-pipe mod, but that was with the OEM primary and secondary cats in place. The cobra X-pipe only has 1 pair of cats (equivalent to the smaller secondary cats on OEM) so will be louder than stock.

Most aftermarket X-pipes I have seen only include 1 pair of cats, so bear in mind you’ll get a check engine light at some point as well. You can remap the car, install a blocking device or just habitually reset it, but it’s worth bearing in mind.

Having heard the Akrapovic system it’s actually not that loud compared to some of the OEM mods.

[benaldo]

Not sure on the level of back box mod on mine but it's nothing major. The one i'm looking at from cobra is this one :

https://cobrasport.com/collections/bmw-m3-exhaust/...

Looks like it still has 2 cats and from the sound videos isn't too crazy.

I saw a video on some guy getting an akropovic and he was disappointed with how quiet it was !

[survivalist]

benaldo said:

Not sure on the level of back box mod on mine but it's nothing major. The one i'm looking at from cobra is this one :

https://cobrasport.com/collections/bmw-m3-exhaust/...

Looks like it still has 2 cats and from the sound videos isn't too crazy.

I saw a video on some guy getting an akropovic and he was disappointed with how quiet it was !

The issue with all the YouTube videos is that the recording device adjusts the levels to the point where it's difficult to comparison of how loud the sound is. I've heard a lot of people refer to the OEM 4-pipe mod as 'ASBO loud', but on videos there isn't a huge difference between the 1.75, 2 and 4 pipe mods.

My M3 actually came with the Cobra cat back installed and when I swapped it for a 2.5 OEM modded box, the volume dropped considerably.

If I was in your position, I'd want to hear the cobra exhaust in real life, as if you don't like it the secondhand vales of these are poor. If you combine the cost of the catted X-pipe and the back-boxes it's over £2k. One of the chaps on m3cutters bought a lightly used full system for £400 and I sold my cat back one for £300 - potentially a fair amount of cash to lose.

[benaldo]

Thanks - lots of good advice there !

[Phateuk]

What's the 2 pipe mod like when at constant motorway speeds? Mine is totally stock now which I like when just cruising around, but when pressing on would like a bit more volume.

Considering the 2 pipe mod but not at the expense of daily driver comfort. (Also is 2pipe mod fine db wise at trackdays?)

[ryanchan]

I have a de cat downpipe which came with the car if you'd like to swap your stock cat with it? V quiet when cruising and pretty dramatic from the outside when pressing on so sounds like what you are after!

[survivalist]

Phateuk said:

What's the 2 pipe mod like when at constant motorway speeds? Mine is totally stock now which I like when just cruising around, but when pressing on would like a bit more volume.

Considering the 2 pipe mod but not at the expense of daily driver comfort. (Also is 2pipe mod fine db wise at trackdays?)

I think many people regard the 1.75 mod as the best compromise if it's a daily driver. It's also supposed to be similar in volume to the M Performance Exhaust (MPE) which was available at the time, although that's made of Inconel rather than steel so sounds a little different. I've got a 2.5 mod on mine at the moment, but it's coming off as the cold starts and volume driving around town is still a bit loud for my liking. Will be going MPE or Akra.

Might be worth contacting Mod Stock (https://mod-stock.co.uk/) and asking their opinion. No affiliation, although I did get my 2.5 mod from him - nice guy and the service was good. Think he does mobile fittings now as well, so you may be able to get it done on your driveway.

[Mach]

I have an e92 M3 exhaust with OEM mod that I'm about to throw out. It did about 15,000 miles on a brand new M3 which I sold with the original exhaust reinstalled. It's in really good condition.

I haven't been able to sell so you're welcome to it for free if you can collect.

[benaldo]

Just to close off this topic, I did buy the cobra performance exhaust which took a good month to arrive and not the expected 2 week lead time. Combined with the modded OEM back box it was loud........ very loud !!! You could drive semi quietly but if you put your foot down over 2k revs then it really screamed - too much for me. However, I bought a 2nd hand standard OEM BMW backbox and was fitted alongside the cobra exhaust and the result is much better. I think it might be slightly quieter than the standard BMW exhaust with modded OEM back box or very close.

So overall a good result and much cheaper than buying a new BMW exhaust system!

Got a spare modded OEM backbox to sell now to get some money back

[survivalist]

benaldo said:

Just to close off this topic, I did buy the cobra performance exhaust which took a good month to arrive and not the expected 2 week lead time. Combined with the modded OEM back box it was loud........ very loud !!! You could drive semi quietly but if you put your foot down over 2k revs then it really screamed - too much for me. However, I bought a 2nd hand standard OEM BMW backbox and was fitted alongside the cobra exhaust and the result is much better. I think it might be slightly quieter than the standard BMW exhaust with modded OEM back box or very close.

So overall a good result and much cheaper than buying a new BMW exhaust system!

Got a spare modded OEM backbox to sell now to get some money back

Good to hear you managed to get something that suits from a volume perspective.

Is your car remapped? If not I believe the check engine light will come on at some point as it has O2 sensors before and after the primary cats - which the aftermarket ones don’t have.

Apparently the mid range power should be a touch better as well, as the primary cats are the most restrictive part of the OEM system.

[The Ferret]

Mach said:

I have an e92 M3 exhaust with OEM mod that I'm about to throw out. It did about 15,000 miles on a brand new M3 which I sold with the original exhaust reinstalled. It's in really good condition.

I haven't been able to sell so you're welcome to it for free if you can collect.

On the off chance that this is still with you, I'm in need of one, and can collect depending on location. Happy to throw in some beer tokens as well.

[benaldo]

When the new exhaust and modded backbox was one the check engine light came on after about 150miles which the garage warned me about but their guy is off at the moment - it doesn't put car into reduced power / limp mode so no big deal. With the current set up, the light hasn't come on yet, but haven't done that many miles yet......

Oil service / MOT next month so will get the light sorted then. I was going to request the 'cold start' option removed as there is barely any Cat to warm up but no need now as it is quieter !