Advice needed with an e46 mod

[indee321]

Hi guys this is my first post here on pistonheads ive read some really good advice and opinions over the last 6 months so thought it was about time i joined in. I know this question has been asked before as ive read and researched as much about it as i can find, but i dont seem to be able to find a good quality 'defininitive' answer.. so here goes

I habe recently bought a 1999 saloon e46 323i. Its immaculate with only 60k on the clock.. so please no ' buy a bigger engine' as im very happy with it.

its an M52TU engine and ive already exchanged the inlet manifold for an M54B30. I would like to know what i can now do with the exhaust sytem to complete the mod. All i would ultimately like to try and do it gain similar hp and torque as the 325i which shouldnt be impossible as they are the same engine capacity. I dont think realistically i will be changing the dif.

I realise the intake and exhaust mod alone wont do this.. the last thing i will do after all mods is rolling road and tune the software.

The 'headers' are restrictive and they contain the cats on these cars so removing them isnt an option for me but as i understand it the e46 323i standard header is the same size as the 328i,is that correct? If it is , there isnt really a great deal of point in going sport or bigger tubing etc as its unlikely i'll be getting anywhere near 328i levels of hp / torque, agreed?

So what are my options for the exhaust from the standard header back? the 323i M52TU is a little unique therefor limited in options? I am wondering what other standard exhausts would replace mine. Is a 328i M52TU exhaust a direct replacement? Or can i use something from the the M54 range, maybe even the whole system including the headers?

Any help much apreciated

[helix402]

Welcome. Have a look on my Readers Car for some E46 ideas. I have a 328i. Without checking my car I don't think it has pre cats in the manifold. I thought these only came on LHD cars or post 2001 M54s. How to get more power? Change the VANOs seals, the best E46 exhaust I've heard is the Alpina one. If you can find a used one it would be ideal. I'm not sure about the M54/M52tu exhaust differences/compatibility, REAL OEM can be useful for this. You can fit a 330i inlet cam to the 328i for more power, should work on the 323 but you'd have to check.
I'm sure if you have the cat manifolds you can swop them for the no cat ones. If you got an aux air pump, bin it. You won't get more power, just less noise.

[indee321]

Thanks for the reply.. so when you say i can swap the cat manifolds for no cat ones.. that means i would need to find a system that has the cats fitted further down the exhaust pipeline right? I dont want to go 'catless' too much hassle at MOT time.
This is why im trying to gain info on an alternative BMW standard exhaust system , say the 328 m52tu .. is that a single or fully duel piped system?
I'll def look into the 330 inlet cam , not heard of that one before.
Has anyone else got any advice about what alternative bmw factory fitted exhaust will fit to allow a better tune up ?

[helix402]

This is the 328i exhaust:



I have checked and my car does not have cats in the manifolds. Or dogs.

Edited by helix402 on Thursday 28th January 14:29

[indee321]

and this is the 323 .. hmm does anyone know if the 328 exhaust manifold will be able to replace mine? Obviously the two systems are quite different , im just wondering why and if there is a bennefit in terms of performance to put a complete 328i onto mine if it will fit..

[helix402]

I don't think you'd gain anything by changing to a 328i exhaust and pair of manifolds. All you'd do is move the cats down to the exhaust, and have to sort the lambda sensor wiring.

[indee321]

Yes comparing the two exhausts i think your right.. someone has suggested to me this exhaust system and it seems reasonably priced. The schmiedmann scm5254 looks like it might just be the option i go for with a little saving up

[helix402]

Looks good.

[indee321]

yep.. the more i look at this the more i feel like its a good option ., just depends on the expense to fit !

[allanhare619]

Hi I have a 323ci e46, and I've come across wanting to do the exhaust and manifold swap too, but checked and it's had the 328 system put on it! Does anyone know if there's big differences in the inlets so I can check to see if this mod may have been done possibly too, what things to look for to see what inlets on it, it's responsive for what it is. So not sure if it's standard especially identifying the 328 exhaust system on it.