E30 Zone

What is the general opinion on the aftermarket exhausts.

I've just had a stainless system fitted and the mid section pipes had to be chopped giving me the chance to gleg inside at the baffles.

The lads at the exhaust place said that baffles in an exhaust restrict gas flow and hinder performance.

They were trying to sell me a powerflow centre box that was basically two perforated tubes with wadding packed around for noise reduction.

Has anyone actually done some rolling road testing comparing OEM
compared to scorpion/BTB/fritze etc.

Am I right in thinking that a free flowing exhaust is good if the engine is flat out all the time but for road use baffles help with back pressure and low down torque?

What do we think?

I thought the louder ones were just louder - apart from the seriously expensive kit from BTB, Alpina etc. The BTB six branch manifold gives 12BHP or so, there are dyno printouts on here somewhere to prove it.

BMW spent millions in R and D,and pretty much got things right.

However,Alpina and other well respected tuners managed to get more out of the M20 with head fettling(talk to Simon13)and different exhaust systems.

Stock system from the dealer will not be a cheap option,but will fit perfectly and 'sound' right.
I have used aftermarket systems from GSF on both of my E30's,one is now well into it's 6th year and is married to the much despised Hottuning manifold.

I love my ECP sourced OEM spec eberspacher exhaust. They sound perfect imo. A nice burbly idle and a bit of a howl up top without anything obnoxious.

Center boxes are generally just perforated tube with baffles round them. They're to get rid of the high frequencies. The back box is two perforated tubes separated by a metal barrier with baffles in between, and these are to get rid of the low frequencies.

apart from the noise when i swapped a scorpion system over from an oem system i didnt notice any power difference, scorpion system on a saloon is fine but in a cab it kills your ears, looks better from the rear with a tec 2 kit, imo thats about it

I've got a fritz bits 6 branch stainless manifold and full system on my 325, haven't had much trouble with it. I changed the whole lot in one go so I can't comment on the power/sound improvements of the system or manifolds individually, but it all seemed to make a difference on mine. Never RR'd either before or after so have no clue about power increases. I'm also using one of speedtouch's 'wild' chips (albeit it with a standard top end) and the car has a vicious input of torque at around 3500 rpm and seems to pull /rev very hard from there on in, which it didn't do before.

It was a fair bit of coin, but seems well put together. My only gripe is that the tailpipes could be a tiny bit closer together but they have grown on me they are quite long aswell, but I kind of like that! IMHO would look better on a non m-tech bumper end car.



There's my two penneth

there is power to be gained from the right exhaust and manifold but most after market systems pre fabricated or made to suit are probably going to lose power if anything over a standard set up. The exceptions are alpina btb and the fritz system and of course if you can find a fabricator who actually understands exhausts they will be able to replicate the successful systems thats a big if though from what i have seen of the pwoerflow style brigade.

daimlerman wrote:BMW spent millions in R and D,and pretty much got things right.

that is always a flawed argument, there are so many more priorities other than performance in BMW's mind so it was never top of the list. This translates to it just not being right for performance like just about everything else on the engine. still alot better than the average one from same era though

but it does mean that performance gains will come at a cost elsewhere....

scott180gtb wrote:What is the general opinion on the aftermarket exhausts.

I've just had a stainless system fitted and the mid section pipes had to be chopped giving me the chance to gleg inside at the baffles.

The lads at the exhaust place said that baffles in an exhaust restrict gas flow and hinder performance.

They were trying to sell me a powerflow centre box that was basically two perforated tubes with wadding packed around for noise reduction.

Has anyone actually done some rolling road testing comparing OEM
compared to scorpion/BTB/fritze etc.

Am I right in thinking that a free flowing exhaust is good if the engine is flat out all the time but for road use baffles help with back pressure and low down torque?

What do we think?

I think they are trying to sell you shit you dont need

I am biased as i run a stainless steel exhaust franchise,but, a well designed system will give you improvements over standard..how much,well that depends.
Your average downpipe back system with correctly spec,d tube size will increase performance ..you might get as much as 5 bhp, more like 2 or 3.The biggest gain will be from the manifold,only the dyno will tell and you will need to do a before and after on the same dyno to tell.
The biggest thing that is tune able is the sound,every system we build has the no likey the sound we change untill you do....we have never had to change a system because the owner did,nt like the sound,we have a massive range of silencers in all sizes and configurations with tube size from 1.5 inch to 5 inch.
The look at the rear end is also important,correct spacings and angles etc.We also consider TIG welding a form of art which looks awesome on the stainless steel which is why we TIG wherever possible and very rarely use the mig.

With one of our systems you get exactly what you ask for ,you dont get this with over the counter stuff.

As PND said you can lose power with the wrong system.

The best result we have had is a 50 bhp gain on a Monaro,it had tube manifolds with true merge collectors hand made in our shop,sports cats and full 2 1/4 inch cat back with custom x piece,the difference was staggering.

cheers Keith

Boysen FTW

DanThe wrote:

scott180gtb wrote:What is the general opinion on the aftermarket exhausts.

I've just had a stainless system fitted and the mid section pipes had to be chopped giving me the chance to gleg inside at the baffles.

The lads at the exhaust place said that baffles in an exhaust restrict gas flow and hinder performance.

They were trying to sell me a powerflow centre box that was basically two perforated tubes with wadding packed around for noise reduction.

Has anyone actually done some rolling road testing comparing OEM
compared to scorpion/BTB/fritze etc.

Am I right in thinking that a free flowing exhaust is good if the engine is flat out all the time but for road use baffles help with back pressure and low down torque?

What do we think?

I think they are trying to sell you shit you dont need

And deffos don't want on your car!

The best place for a Scorpion zaust is the skip , though I would try the classifieds first

reggid wrote:

daimlerman wrote:BMW spent millions in R and D,and pretty much got things right.

that is always a flawed argument, there are so many more priorities other than performance in BMW's mind so it was never top of the list. This translates to it just not being right for performance like just about everything else on the engine. still alot better than the average one from same era though

Yesss,but...

The point that I was trying to put over was that an OEM system from the cylinder head back WILL fit perfectly,once you wander into the murky world of aftermarket you have to expect fitting issues that require solving,but the reward could well be a small performance boost.
In the main,BMW seemed to have done a reasonable job,bearing in mind costing,performance,fuel economy etc.

Seem to remember that Alpina found a little more power with an alternate exhaust system,but when these are available the price is in the region of;

'HOW MUCH?'

In the olden days when I was a lad a stainless steel exhaust was the Holy Grail of exhaust systems...'they last for ever,lad,never have to buy an exhaust again'...was the selling pitch.This was against a background of mild steel systems that may last two years if one was lucky.

These days,the mild steel systems do seem to be far more durable,as I stated above,I have a system on the cabbie that I transfered from my moredoor,bought new at least 6 years ago and still sound.

Only ever had 1 "performance" aftermarket exhaust - a full Janspeed system on my 16v Astra GTE. Loved it for about a week and then it started to get annoying.

Standard FTW.

the only proper performance exhuast is alpina imo. i know i'm biased but there work on the M20's was majored on the exhuast side of the engine when the intake side of it was up to the job and was left standard.

Scott they're full of sh!t just trying to sell you some sh ! te you don't need. Sounds like a quik fit outfit.

Tell um to shut the f**k up and do what you've asked.

Does anyone find the stock BMW exhaust too quiet ?

Btw what do u people think of bosal exhausts for sound ?

If I drill a hole will it sound louder ?

IMO and at the risk of sounding like a bruv the LOUDER the better. I wanna get 100dB from the E30 exhausts

I heard Scorpion r quite good not sure if true or not

Anyone got any photographs of what Alpina exhaust on 325i looks like as they seem to be quite respected on here ? How much are they ? Does it reverb in narrow streets or tunnels ?

I know the stock BMW I think the exhaust exit the rear at an angle

I bought my 325 with a scorpion system fitted by the previous owner. It's a little loud at times for my old ears and I don't like the exhaust note, it's too high. You cruise along at about 3000 rpm and it sounds like the engine is revving much higher.

Genuine exhausts are awesome. When most e30s as are running pattern exhausts or aftermarket ones and you switch to a genuine one you will see how good it is.

daimlerman wrote: In the olden days when I was a lad a stainless steel exhaust was the Holy Grail of exhaust systems...'they last for ever,lad,never have to buy an exhaust again'...was the selling pitch.This was against a background of mild steel systems that may last two years if one was lucky.

These days,the mild steel systems do seem to be far more durable,as I stated above,I have a system on the cabbie that I transfered from my moredoor,bought new at least 6 years ago and still sound.

... Except for when they used mild steel mounts, baffles and welding wire and all that was left was some stainless pipe dangling from your rear bumper.

Blitz wrote:Genuine exhausts are awesome. When most e30s as are running pattern exhausts or aftermarket ones and you switch to a genuine one you will see how good it is.

My Bosal one isn't too bad. The fit's a bit off but there's a bit more adjustability with a single pipe system. As for sound, its very quiet, to the point where my intake side is louder than my exhaust side.

Loud exhausts are all fun and games until you do a 100 mile motorway journey and realise you'd rather get the train back.

Hi everyone i just joined but i have a supersprint exhaust and i Love it. awesome sound and i did notice a little more power with it. and the fit is perfect but its the one designed for the e30.

The fact that the original exhaust lasted so ling says it all really compared to the aftermarket.

My old 325i sport was i sold in about 2006 had its original exhaust, still not rotton. It wasn't the only one about like that.

Alpina systems are mainly NLA but if they get 6 orders then they're about £1000

I just love the reverb in my exhaust
Sounds epic
Slightly coarse
Reverb under train bridges tunnels streets and off walls off parked cars or buses
Ask Barry

Seems louder when a car is on one side of the car than the other

Louder than E46 M3 CS !!!!

U can drive round at 30 mph in 1st gear and everyone looks

pony wrote:U can drive round at 30 mph in 1st gear and everyone looks

Do you really want to drive around with everybody looking and thinking "what a complete and utter prat"?

pony wrote:I just love the reverb in my exhaust
Sounds epic
Slightly coarse
Reverb under train bridges tunnels streets and off walls off parked cars or buses
Ask Barry

Seems louder when a car is on one side of the car than the other

Louder than E46 M3 CS !!!!

U can drive round at 30 mph in 1st gear and everyone looks

Do you have to compare everything to an e46 M3????? It ain't 'lf boring!


Si, if you remember the red 325 we broke from the BMW tech, he'd only just put a complete BMW system on that to replace the original! And thats the system Bazza has on the sport now.

Original systems are epic. And the way to go.

I have a genuine system on the C2, it's by far the best option, Barry has the BTB on his with the centre and rear sections of the three piece system, this is what I was hoping to go with minus the BTB, sadly the front section is NLA, this is why I ended up going two piece, no regrets though, sounds great, I do have a Janspeed Alpina manifold which needs a bit of love, in the future I hope to use this. I do still have the Alpina single piece leaning up against the wall at work, if the option had been there I would have got another i'm not ordering 6!!!

pony wrote:I just love the reverb in my exhaust
Sounds epic
Slightly coarse
Reverb under train bridges tunnels streets and off walls off parked cars or buses
Ask Barry

Seems louder when a car is on one side of the car than the other

Louder than E46 M3 CS !!!!

U can drive round at 30 mph in 1st gear and everyone looks

You can't see what they are thinking!

Haha I thought my comments would be a bit marmite

I want to hear what an original BMW exhaust sounds like.

Hopefully Barry will take me for a drive sometime in his Sport

Brianmoooore wrote:

pony wrote:U can drive round at 30 mph in 1st gear and everyone looks

Do you really want to drive around with everybody looking and thinking "what a complete and utter prat"?

I don't let what people think bother me as long as I am enjoying myself

pony wrote:

Brianmoooore wrote:

pony wrote:U can drive round at 30 mph in 1st gear and everyone looks

Do you really want to drive around with everybody looking and thinking "what a complete and utter prat"?

I don't let what people think bother me as long as I am enjoying myself

You'd love a Peco BB4

The best sounding 325i I ever heard was the Gug.

pony wrote:I just love the reverb in my exhaust
Sounds epic
Slightly coarse
Reverb under train bridges tunnels streets and off walls off parked cars or buses
Ask Barry

Seems louder when a car is on one side of the car than the other

Louder than E46 M3 CS !!!!

U can drive round at 30 mph in 1st gear and everyone looks

I had an exhaust like this on a 1989 astra gte 16v set off alarms everywhere POS I have learnt my lesson since though.