What'sthe right exhaust for performance and sound

[jgoodd]

Question: I've been reading through the different exhausts out there on the web and this forum and I haven't really found the answer I'm looking for. So far all I can tell is that some manufacturer blow their HP gains way out of proportion and others make you wonder why you would by them other then changing to an awesome sound (don't forget a lot of money). Hopefully someone may have some input out there that is helpful or at least may send me in the right direction.

So here is what I have, 2008 M3 convertible with 22k miles. I've already upgraded my ECU to the Dinan S1 with the intake and pulleys. I've looked at the following exhausts:

AKRA - 3HP gain and 4LB/FT
Dinan - 6 HP and 5LB/FT
MRF 56HP and 46LB/FT (seems like a crazy difference)
eisenmann 16HP and 11LB/FT

I've looked at a few others, but I think I'm getting to the point. Outside of looks and sound has anyone put one of these on and noticed or Dyno'd their cars?

I would say that I think I'm going to use the Dinan S2 software once I put the exhaust on and that may change the results anyway, but once all that is done I'll post the Dyno results.

Thanks in advanced for the input.

[Krozi]

What are you looking for? A batshit crazy "I will f**k you in the face" kinda exhaust or a nice mellow upgrade over stock? Or sporty/somewhat aggressive but still daily-drivable exhaust?

For reference, this is a batshit crazy "I will f**k you in the face" kinda exhaust:

[blackbeast535]

This should help

http://www.m3post.com/forums/showthread.php?t=328915

[jgoodd]

I saw that exhaust online and it does sound good, but what's the gain? If you're going to spend 3k+ it seems that getting more then 3-5HP and 3-5 LB/FT is a must. I know there is just as much performance increase with the X pipe replacement, but that will be next.

[jgoodd]

Thanks BB, I think I will see if I can track down some of the performance ratings on those exhausts.

[blackbeast535]

I was in the same boat as you were. I wanted a system that does not drone so I went with Dinan. All of these systems will make the same amount of power with just the rear muffler section. You need to remove the primary cats to make more power, then you will also need a tune for CEL but may also have to worry about emissions. It all comes down to how loud you want to make your car. You can always start with a rear muffler and add an x pipe for more sound. Good luck.

[radiantm3]

Don't forget with the akra (and bmw performance) you are losing a good 40-50lbs which is pretty significant.

[Ateam]

I think you have to go into buying an exhaust with expectation to gain NO horsepower or torque or performance other than potential mild weight savings. Depending on the system there is probably a coupe hp here or there with a rear section but really nothing you would ever notice.

The primary reason you are buying, or should be buying an exhaust is to enhance your enjoyment of the sound of your car. You have to be one to turn off the music and want to listen to your exhaust a lot of the time. Even hypothetically if a rear section gave you 30 more hp, I would still take an exhaust that sounds great, rather than something that did not for more hp.

Point is that sound adds a LOT of enjoyment to your overall experience of driving and if it does not than an exhaust may not be the best use of your money.

[Vybz]

Your numbers for MRF Velaforza are way off. 28 RWHP 22RWTQ

http://www.mrfengineering.com/2011/02/mrf-velaforza/


The RPI GTM ( Exhaust in Krozi's vid) is 28RWHP AND 35RWTQ. You're shelling out 2.75k for the exhaust, but it's undoubtedly the best bang for your buck. Personally I'm going the GTM route, but it's obviously not for everyone as Krozi said.

[Ateam]

Are we talking 30 hp with a full catless system? I can believe that. Any system with cats in place that is not even a remote possibility. I don't think the OP was set on deleting his cats and was open to just a rear section as well no?

[BMW Fanatic]

WOAH. Is that the full exhaust system from RPi or just the axle-back? Assuming it's the whole shebang but you can never know these days.

Also, would you guys says the Eisenmann Race w/Challenge x-pipe is louder and deeper or near the same?

[Krozi]

Originally Posted by BMW Fanatic

WOAH. Is that the full exhaust system from RPi or just the axle-back? Assuming it's the whole shebang but you can never know these days.

Also, would you guys says the Eisenmann Race w/Challenge x-pipe is louder and deeper or near the same?

The vid above is the full catless race exhaust. Called RPi GTM

And I don't think Eisenmann is deeper. To me they've always been known to be a bit more pitched IMO

[BMW Fanatic]

Originally Posted by Krozi

The vid above is the full catless race exhaust. Called RPi GTM

And I don't think Eisenmann is deeper. To me they've always been known to be a bit more pitched IMO

KROZI! THANK YOU! I honestly think I have found my next exhaust system, I'm getting the OEM mod done just to see how it sounds but the RPi GTM Full Catless Exhaust system is definitely what I'm gonna go for come January and my 21st birthday present to myself!

[M3ryder55]

WOW that rpi sounds amazing..... might be a lil too loud though for me. but wow sounds incredible. how much does that system add to the rear wheels roughly?

[Sales@Evolve]

A CAT Back / Axle Back system adds very little HP.

Different manufacturers claim different things based on how consistently they test and how much marketing they want to implement.

The basic engineering facts are that by removing the front catalytic converters you reduce back pressure by 0.5bar and this is the main way to increase power.

If you have a 0.5 bar pressure point at the front cats then what difference is a rear silencer going to make!

Another fact for you. The rear OEM silencer poses very little back pressure and flows extremely well.

We have cars running with Akra / Evolve / AA X Pipes with OEM rear making exactly the same power as those with the same X Pipes and after market rear sections.

I would have thought people can see the above from the massive amount of data already available.

[Krozi]

Originally Posted by BMW Fanatic

KROZI! THANK YOU! I honestly think I have found my next exhaust system, I'm getting the OEM mod done just to see how it sounds but the RPi GTM Full Catless Exhaust system is definitely what I'm gonna go for come January and my 21st birthday present to myself!

Hahah right on!

Originally Posted by M3ryder55

WOW that rpi sounds amazing..... might be a lil too loud though for me. but wow sounds incredible. how much does that system add to the rear wheels roughly?

It is a very loud exhaust that's for sure...maybe not ideal for city driving haha...

I dyno'd before and after but on different dyno's so the numbers aren't accurate. Although both were Dynojets, I dyno'd 335whp on a mobile dyno and 378whp after the exhaust at a shop dyno. The exhaust did not add 43whp. That is simply not possible. I think the mobile dyno I went to read really low...335whp is pretty low for stock. So realistically I'd say I gained about 30whp. I recently put down 390whp after I got the ESS Tune.

RPi definitely has the best bang for your buck factor. Our cars aren't cheap to modify, especially being NA. So $2800 for the exhaust + $1000 for the tune isn't bad for 390 wheel

Originally Posted by SehrSchnell

Holy f@ck! That sounds amazing!

Thanks man!

[Genericuser1]

Originally Posted by Krozi

Hahah right on!



It is a very loud exhaust that's for sure...maybe not ideal for city driving haha...

I dyno'd before and after but on different dyno's so the numbers aren't accurate. Although both were Dynojets, I dyno'd 335whp on a mobile dyno and 378whp after the exhaust at a shop dyno. The exhaust did not add 43whp. That is simply not possible. I think the mobile dyno I went to read really low...335whp is pretty low for stock. So realistically I'd say I gained about 30whp. I recently put down 390whp after I got the ESS Tune.

RPi definitely has the best bang for your buck factor. Our cars aren't cheap to modify, especially being NA. So $2800 for the exhaust + $1000 for the tune isn't bad for 390 wheel




Thanks man!

At steady 60-70mph how is the drone. Also since it's catless do you need to put on a different exhaust every time you need to go to emissions testing?

[Krozi]

Originally Posted by Design1stCode2nd

At steady 60-70mph how is the drone. Also since it's catless do you need to put on a different exhaust every time you need to go to emissions testing?

Not bad at all. That speed puts you right around a steady 2600rpm where there isn't a lot of drone. The drone is at 2000 and 3000.
And Florida doesn't have emissions testing..but yes you would need to put the stock exhaust back in.

[ModBargains III]

The weight difference will be the most significant thing... To be honest there isn't a whole lot of power to be made just from a rear section muffler. I would suggest, rather, to find an exhaust that sounds the best to you, and then going with that one. That's probably your best bet to being satisfied.

[Peahi]

Originally Posted by Ateam

I think you have to go into buying an exhaust with expectation to gain NO horsepower or torque or performance other than potential mild weight savings. Depending on the system there is probably a coupe hp here or there with a rear section but really nothing you would ever notice.

The primary reason you are buying, or should be buying an exhaust is to enhance your enjoyment of the sound of your car. You have to be one to turn off the music and want to listen to your exhaust a lot of the time. Even hypothetically if a rear section gave you 30 more hp, I would still take an exhaust that sounds great, rather than something that did not for more hp.

Point is that sound adds a LOT of enjoyment to your overall experience of driving and if it does not than an exhaust may not be the best use of your money.

Well spoken man. My car has a m-performance...and the sound is just money. I have an exhaust on another vehicle that drones. I was actually ok with that, but now I'm driving something that does not drone, it sucks to go back and drive the "droner."

[Vybz]

lol it sucks you live on the other coast Krozi I really want to hear the GTM in person, and I don't think there is anyone in the state of WA that even has the exhaust. I'd pull the trigger on the exhaust regardless, but still just to relieve doubt, it would be nice to hear in person.

I didn't have any doubt before, but unfortunately this thread made me remember the MRF full catless, and while the torque output is less, the higher pitch sound is more to my liking... so yea... back to square one? haha

[soberin]

I have the Dinan intake and exhaust. The interest is mainly aesthetics and a bit of sound. Certainly not power. My Dinan Stage III suspension is a lot more important to my enjoyment of the car than the exhaust.

I would point out that unless you are going catless, the M3 is really known more for it's mechanical growl under power, which turns into a real snarl at high revs. My point being is that most of the enjoyable noises from this vehicle come from the FRONT, rather than out the exhaust. If you really want noise from the exhaust, go catless with a crazy system, or buy a C63 or a Shelby Mustang GT500.