which exhaust system offers the biggest gains?

[niqui]

hi,
i am wondering which bolt-on exhaust system offers the best gains?
loud ones excluded, but please post their gains if you know them.
ive been told certain systems offer gains of 15hp, whereas others offer 30hp+...
on a stock car, without any other changes, cats and all that stay in.
My view is that this is the safest way, in terms of warranty, to get more out of your car...correct me if i am wrong.

thks

i was recommended the eisanmann sport, but have heard of gains all over the place, the aa one is also supposed to offer good gains.
i just thought it would be easier to have them all in one thread.

[Nawaaz]

If you want something on the quiet side, yet still gives you good power, then go with the AA signature. The problem is that some members who ordered the AA expected it to be pretty quiet, but it was slightly louder than they expected once it was installed and tried out. But overall, the owners were happy with the sound. In truth, almost any aftermarket high-performance exhaust that you install will at least always be slightly louder than stock. I think the AA would be your best bet.

[powertrip]

In most cases differences in power between systems is going to be like splitting hairs. You should go with the system that sounds the best to you because you'll be living with it on your car every day. If you really want to make power I would suggest at least buying a system with connecting pipes. AA is great and not too loud, but it is deep below 3k rpms.

[M3 Montreal]

Originally Posted by niqui

hi,
i am wondering which bolt-on exhaust system offers the best gains?
loud ones excluded, but please post their gains if you know them.
ive been told certain systems offer gains of 15hp, whereas others offer 30hp+...
on a stock car, without any other changes, cats and all that stay in.
My view is that this is the safest way, in terms of warranty, to get more out of your car...correct me if i am wrong.

thks

i was recommended the eisanmann sport, but have heard of gains all over the place, the aa one is also supposed to offer good gains.
i just thought it would be easier to have them all in one thread.

NO ... ZERO...None... NAda... muffler alone offers 30+hp... The 30+HP is going FULL including X-pipe and catless.

For what you want I would recommend the Eisenmann Sport (not the race). I would tell you AA but I never heard mine without the cat so I cant say and others have said they find it loud.

[montreal red]

Originally Posted by M3 Montreal

NO ... ZERO...None... NAda... muffler alone offers 30+hp... The 30+HP is going FULL including X-pipe and catless.

For what you want I would recommend the Eisenmann Sport (not the race). I would tell you AA but I never heard mine without the cat so I cant say and others have said they find it loud.

+1
there's no way you can gain 30 hp with just axle back...

if you dyno your car before and after an axle back swap, i can say for sure that it is unlikely that you will get anything close to 15hp with just an axle back. and anything below 15hp is prob very difficult to feel in terms of acceleration. people change axle backs for sound more than for gains. if you want gains, you'll need to do what m3 montreal has.

btw, isnt this like your 2nd thread you posted on mufflers!! hurry up and decide !! eisenmann sport is a great way to go. you should check out the eisen threads -- it seems like no one has any regrets with that system (except for the fact that some say its too soft).

[MrHarris]

RPi and Gintani -- end thread.

With a full system from either one, expect 20-25whp, and 20-30wtq.

[niqui]

Originally Posted by montreal red

+1
there's no way you can gain 30 hp with just axle back...

if you dyno your car before and after an axle back swap, i can say for sure that it is unlikely that you will get anything close to 15hp with just an axle back. and anything below 15hp is prob very difficult to feel in terms of acceleration. people change axle backs for sound more than for gains. if you want gains, you'll need to do what m3 montreal has.

btw, isnt this like your 2nd thread you posted on mufflers!! hurry up and decide !! eisenmann sport is a great way to go. you should check out the eisen threads -- it seems like no one has any regrets with that system (except for the fact that some say its too soft).

actually, i was thinking of doing it more for the performance gains than the sound, i dont care about the stock one, it sounds fine to me, so i was changing to give more juice...which clearly is pointless.
i stopped in terms of an exhaust cause i was gonna do the ecu on july 12th with you, but now i think not with all the warranty crap i read, so i thought an exhaust could give me similar gains yet keep my engine warranty.
i dont know, if its mainly for sound, id rather buy the performance steering wheel.

thanks guys.

what exactly does a "full system" include?

[jml]

Removing your muffler (cut outs) will technically offer you the most opportunity for gains. I doubt there is anything to write home about though. I certainly don't feel any improvements cut-outs open or closed.

IN FACT on the E46 it was proven that the stock mid pipe offered the most power gains when the cats were removed over all other mid pipe designs on the market at the time. BMW is not stupid and unlikely to be leaving HP on the table for the criteria they are designing to.

If you want power gains, get rid of all 4 cats. That is clearly a design constraint that when removed creates a big opportunity.

[niqui]

Originally Posted by jml

Removing your muffler (cut outs) will technically offer you the most opportunity for gains. I doubt there is anything to write home about though. I certainly don't feel any improvements cut-outs open or closed.

IN FACT on the E46 it was proven that the stock mid pipe offered the most power gains when the cats were removed over all other mid pipe designs on the market at the time. BMW is not stupid and unlikely to be leaving HP on the table for the criteria they are designing to.

If you want power gains, get rid of all 4 cats. That is clearly a design constraint that when removed creates a big opportunity.

thanks, i guess i figured it out, its a waste of money to buy a 3k exhaust if i plan on leaving cats and all that in place, in terms of performance gains.

[montreal red]

Originally Posted by niqui

thanks, i guess i figured it out, its a waste of money to buy a 3k exhaust if i plan on leaving cats and all that in place, in terms of performance gains.

yeap... you got it right. if youre not doing it for sound and you like the stock sound. dont mod the exhaust!! its not a good place to get extra power. i think for you, the ecu is the best bet in terms of gains.

i have a different set of priorities. for me, i think the car is fast enough. i love sound so i changed the axle back section (going to change it again soon to something else!)... for those people who want the most gains by doing an exhaust mod, they'd have to do more than axle back. they'd have to do header back and prob remove the cats while putting an x-pipe on.

the downside to a full set up? you'd have to get a tune to clear your CEL. or find another way to clear it yourself. or use lamda adapters.

[MrHarris]

ECU + Full exhaust = massive gains