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      12-13-2011, 06:33 PM   #1
CHLNGM3
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Info on RPi GTM Race Exhaust?

Hey guys! I am about to pull the trigger on an RPi GTM Race Exhaust for my 11' e92 M3 and i'm wondering if there is anyone on the forum who has this exhaust? They advertise gains of 28hp and 35ft/lbs. Are these realistic or just a bunch of bologna? Please give me some advice. Thanks!
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      12-13-2011, 06:37 PM   #2
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Talk to Krozi. He's dyno'd his car since install and based off the figures it would seem the gains are legit.
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      12-13-2011, 06:48 PM   #3
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Thanks!! I'll make sure and talk to him.
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      12-13-2011, 07:02 PM   #4
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Eyyyyooooooo
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      12-13-2011, 07:13 PM   #5
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Well hey there Krozi!!!! So I would like to ask you a few questions. First off how do you like the RPi exhaust? Is there anything you don't like about it? Have you had any problems? Thanks again for the reply!
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      12-13-2011, 07:31 PM   #6
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I have the same exhaust and it's loud. Sounds orgasmic but the drone is unbearable at least to me. I'm thinking of changing my slip on to akra but I'm worried about losing the great sound.
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      12-13-2011, 07:32 PM   #7
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Btw I'm prbly gonna sell the exhaust so let me know if your intrested!
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      12-13-2011, 07:42 PM   #8
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lol do all the GTM owners live on the east coast??? Can't wait to go home for Christmas, I'm listening to one of your exhausts.
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      12-14-2011, 01:52 AM   #9
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Had the full header back GT system and it was really bassy, really, really raspy and super loud! The GT mufflers had the pipes come in to the sides of the muffler cans and it caused a really bad ringing sound. I have heard the new GTM system and its much cleaner but drones a lot. I currently have the RPI GT x pipe with resonators I installed mated to Fabspeed mufflers and I love it. The mufflers tamed it down to a reasonable level. The GTM is a track only exhaust which makes great power but is far too loud to live with IMO.
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      12-14-2011, 06:48 PM   #10
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I've been kinda planning on writing a little review on the exhaust...I figure this will do the job.
Ok here we go performance-wise...

Before the GTM Exhaust I got my car dyno'd at a Mobile Dynojet and put down 335whp/250wt. A few months later I got my car dyno'd again at a different shop, also on a dynojet. This time I put down 380whp/267wt.

These results kind of baffled me since I gained 45whp but only 17wt.
I honestly do not think I gained 45whp from the exhaust, but gaining only 17wt also didn't make sense to me. I think the reason for this inflated whp gain could definitely be dyno conditions and correction factor. The runs on the mobile dynojet yielded pretty low results. This was possibly due to the laughable little fan they had set up and the 1.00 STD Correction Factor they used. The other dynojet I went to after I got the GTM installed had a much better fan and used a 1.00 SAE Correction Factor.

Since the whp numbers were so high, I was expecting the wt numbers to be much higher also. Unfortunately the wt was only 17wt higher than stock. There are two factors I think I can attribute this too... First is that the Mobile Dyno used 3rd gear in their pulls, and the other Dyno used 4th gear. The second is the fact that RPi uses a Dyno Dynamics Dyno to measure gains instead of a Dynojet. So either those 2 factors have something to do with it, or the exhaust simply doesn't make the torque gains. But I think that the difference in gear choice might have caused this.

I would have really preferred to use the same dyno to measure the power difference...unfortunately this wasn't the case...so I don't know how credible the numbers are.


Sound wise, yes, it is a REALLY loud exhaust. But it sounds insanely awesome
A very, very aggressive and vicious sound! At the same time it does have very considerable drone. On the highway it's not terrible, and cruising around 60mph isn't bad either. Where you really notice the drone is in varying traffic speeds and slow speeds.

That being said, I do daily drive the car with the GTM exhaust and I'm able to deal with it. I am looking to quiet it down a bit though...to do this I'm going to install the OEM x-pipe with the Turner Test pipes primary cat delete. That should tame down the exhaust a bit
I'm probably going to flip-flop between these two exhaust setups often cause I'll miss the insane sound hahah
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Last edited by Krozi; 12-14-2011 at 08:29 PM.
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      12-15-2011, 01:49 AM   #11
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Thanks Krozi for the fantastic review and reply!!! I have one more question that probably isn't necessary to ask but does the exhaust void any factor warranties?
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      12-15-2011, 10:34 AM   #12
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Quote:
Originally Posted by CHLNGM3 View Post
Thanks Krozi for the fantastic review and reply!!! I have one more question that probably isn't necessary to ask but does the exhaust void any factor warranties?

No problem

There really isn't a definitive answer to your question unfortunately.
It really depends on the dealership and what the specific problem is. My dealership really doesnt care, but if a regional BMW rep showed up, he could void my warranty in a heart beat!

But it'll be fine! Most of the SA's and techs will be too busy enjoying the exhaust to think about voiding your warranty
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