325i exhaust: standard vs. modified

[VolksPikey]

Hi,

I've just put my 325i in for an MoT (only bought it a couple of weeks back) and as expected, the exhaust was blowing. They tried to get hold of two new sections but couldn't, so just resorted to welding it for now. But in time, it will need replacing.

I'd like to try to free up a little bit of power (I know just changing the exhaust won't result in huge gains), but I don't know the decent aftermarket systems from the rubbish ones. I'm assuming at least a small amount of BHP could be gained from switching to a six-branch style manifold as opposed to the standard cast manifolds. I like the standard sound and I figure that BMW knew what they were doing when they designed that exhaust for that car. I don't want to mess with it too much (it's a gem of a car) but before I go looking for another standard system, it doesn't hurt to look at the other options.

So what I'm wondering is, can anyone recommend a decent aftermarket performance exhaust that's worth putting on an otherwise standard 325i? Alternatively, would it be worth looking for a system from a Sport (if it was even any different)? Or would I be best just replacing the knackered one with another standard one?

Cheers,
Graham.

[don-king]

IMO the scorpion stainless steel exhaust is a good option........

[jmc330i]

Heres a quote from another thread....

Sebring exhausts are famous for their motorbike systems but their car stuff is second to none. The back boxes are a bit gay in their tailpipe design very german and angled wrongness. I guess some like that!

Alpina system is like a bmw one but the pipework bore is 50mm - same as an M3 instead of 44mm plus the silencers are different internally. Best performance M20 system there is. They sound fantastic

People diss scorpions but they sound better as the baffles die and break down! no gain in power but what a noise!

Walker/Bosal and any other kwik fit style exhaust are a load of toilet that won't last or sound very good.

Finding a decent quality exhaust for an M20 invariably leads you back to the main dealer! £360 for the full system iirc in 3 piece form is a pretty good price if you ask me. Will last 15 years too

A 6 branch manifold will help power and sound. It must be a good one, but they will be expensive (BTB, racing dynamics if you can find one). If you want to go for a 6 branch manifold, get a 3 piece exhaust system as most 6 branch are designed to fit these.

My 325i Sport still has it original exhaust (albeit now fitted on my touring), and its still going strong after 18 years - it looked a bit flaky when I took it off, but a rub down and coat of paint sorted that.

Alternatively, would it be worth looking for a system from a Sport (if it was even any different)?

All 325i exhausts are the same.

[fuzzy]

what was it bss325i fitted to his? a genuine 6 branch , (btb2 or similar?) and a scorpion system? it gave him 185bhp and 190lbft iirc. a big increase from just an exhaust system.

[VolksPikey]

Thanks everyone for the responses.

I'm assuming the Alpina system is quite rare and therefore quite expensive?

I think I may have to end up just seeking out a good 2nd hand system from somewhere, mainly on cost grounds. It's a bit annoying as I'd love to have to some more power to play with.

It does look like I've had a lucky escape though: when the garage phoned me up and said I'd need two new exhaust sections, one costing £109 and the other £121 (pattern parts), I told them to go ahead and order them. But I spoke to them again yesterday and as they couldn't get hold of them, they just welded it up instead. Probably a good thing, otherwise I would have forked out £230 for stuff that probably isn't that good.

Thanks again for your help. At least if I stumble into a pile of money, I have a good idea of what to look for exhaust-wise!

Graham.

[djk]

what was it bss325i fitted to his? a genuine 6 branch , (btb2 or similar?) and a scorpion system? it gave him 185bhp and 190lbft iirc. a big increase from just an exhaust system.

Definitely BTB2, and I think you're right on the Scorpion. BTB2 manifolds are c.£700(!!), but probably worth it if you're after the best. Hottuning do a six-branch for much less, but it would seem they offer no power gain over the standard log manifold. Reputedly, they do affect the timbre of the exhaust note for the better, if that's your thing.

[hongkongfuey]

the hottuing ones are £200, they are a btb copy, i have one of these and am happy withit, i'm not going into power figures as that arguement has had its day, but it looks nice and sounds nice, i also have a fritz's bitz stainless system