335i exhaust - to mod or not to mod?

[mistergee]

ok peeps, just got an 06 335i in tourer flavour. great car but it needs to sound fruitier. With the expense of buying it i dont have money for a complete system and stumbled on this:

http://www.m3post.com/forums/showthread.php?t=511380

got me thinking i could buy some cans, open them up and remove the stuffing, maybe plug the perforated pipes, refit and voila.

so i found these on ebay....

http://www.ebay.co.uk/itm/BMW-E92-E93-Coupe-Convertible-335i-Exhaust-Centre-Back-Box-Silencer-catalyst-/400327582761?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5d35622429


i guess the back box would need to be cut off to make it fit due to the difference in length of cars. Does anyone have experience of this kind of mod? Am i on a hiding to nothing?

all comments welcome - thanks

[172]

links dont work for me

but enjoy the car as it is. plenty of time to realise modifying it wont make the car any better later

[mistergee]

mmmm, not sure why the links dont work. now tried the infamous 'golf tee mod' which has worked a treat for literally 60 seconds work. well pleased but more work needed i think!!.

To be honest the way the car sounds does make a difference in the overall enjoyment (for me)- but its all subjective and personal choice.

[Steve_D]

mistergee said:

ok peeps, just got an 06 335i in tourer flavour. great car but it needs to sound fruitier. With the expense of buying it i dont have money for a complete system and stumbled on this:

http://www.m3post.com/forums/showthread.php?t=5113...

got me thinking i could buy some cans, open them up and remove the stuffing, maybe plug the perforated pipes, refit and voila.

so i found these on ebay....

http://www.ebay.co.uk/itm/BMW-E92-E93-Coupe-Conver...


i guess the back box would need to be cut off to make it fit due to the difference in length of cars. Does anyone have experience of this kind of mod? Am i on a hiding to nothing?

all comments welcome - thanks

Try the links now.

Steve

[mistergee]

thanks steve

[Mr Whippy]

mistergee said:

mmmm, not sure why the links dont work. now tried the infamous 'golf tee mod' which has worked a treat for literally 60 seconds work. well pleased but more work needed i think!!.

To be honest the way the car sounds does make a difference in the overall enjoyment (for me)- but its all subjective and personal choice.

I totally agree.

When I bought my Z4 I wasn't so impressed, and after a few weeks I was pretty mortified that a big 6 cylinder BMW engine could sound like a thrashy 4 pot.

Fortunately they have the sound generator which helps matters.

But it was still a bit naff. I spent £170 having de-secondary cat pipes made (not sure if the 335i has anything similar) and they really improved the edge to the sound. It passed the MOT this year without them, but only just. Last year it only just failed and had to have them fitted.

Woofles on the over-run now crack occasionally, quite loud sometimes, so it's starting to sound like any sports car engine should. It's generally a bit sharper and just sounds like a decent 6 pot BMW engine did in the 80's as standard. Possibly a touch too refined still.




It's pretty hard to tell from the eBay pic but it looks like the 335i runs an active exhaust on the offside exhaust outlet.
There is only one cross-over pipe so I'm guessing that the system is balanced for when it is closed, so cross-over pipe flows from the offside box to the nearside one.
Then when the valve opens the offside box can flow much more freely to atmosphere, relieving the nearside box of the extra flow and allowing that one to flow more easily too.

I definitely would try get a system to cut up. Chances are you can open up that offside box and see how it works. It'll be double skinned so prepare to have to kinda bodge it back on (try cut the outer skin first a bit bigger, then the inner skin a bit smaller)... or just chop that up and use it as spares/pipes of same diameter and reference for when you mod your own.

There is a good chance you will spend about £150 and learn a lot and get an exhaust system that does exactly what you want it to, and benefit from the OEM design benefits with regards to tuning to remove unwanted noises and resonances.

Generally just de-packing silencers, adding more holes, or covering them up etc is all you need to do to get the sound you are after. Big shiny stainless steel just adds expense and often removes the important sound-engineering the OEM did.

OEM exhaust mods for the win

Dave

[mistergee]

Cheers Dave

love the fact that you can get a bit of over run going on, was talking to an bmw tech who reckoned that it would be nigh on impossible to get the 335 burballing. Booo!

Bit sh$t swapping decat pipes in and out if you dont know a friendly garage but i guess its once a year only. I have a similar faff with my motorbike but at least thats 10 minutes and 2 bolts!

Glad you think this is the right thing to do; the plan is to keep all the cats and resonator chambers as standard and just modify the back box. Thats way i should be able to get something not too loud. Something with purpose but doesnt drone like moaning hippo above 60 on an even throttle.

Probably start with opening up both sides to the exhaust close up the holes but keep the stuffing in - i can then take out the stuffing if i need to. I have already disconnected the vacuum hose so both cans work all the time.

Just need to get a doner exhaust now!

[Mr Whippy]

Yeah finding a donor exhaust is the hardest bit really. BMW exhausts are usually all in ones at first and so massively long and pretty damn heavy too haha.

I managed to get mine from the Midlands to Leeds for about £200 which was really good imo.


Since my insurance covers exhaust mods I'm gonna have a go at doing more mods to mine soon. I really want to start checking the noise levels inside and out as I mod along (recording with fixed audio gain so you can compare properly), and also any differences in power.

I think there is a little bit of power and a lot of extra noise quality to come from these modern BMW engines.

My uncle used to have an old Alpina with a straight six (80's model) and it wasn't loud but just sounded so characterful and cultured. Todays sixers seems somewhat muted really. I have no idea why. I think the 335i are not so bad by all accounts, but my Z4 was pretty naff out of the box hence my desire to mod... but avoid the £500+ stuff you can get where the providers offer no kind of money back guarantee or before/after indication of sound quality or volume, drone etc.


Dave