Jray68

Hey Guys, I have an all stock 99 z28 m6, 79k miles. I had a brand new gmmg / madhammer catback installed on it last week. Love it, It sounds great- BUT....... I've noticed at rpms above 3k, and at wot, the exhaust note is actually quieter than when under 2500 rpm? You can hear the exhaust but it really thins out and doesnt scream, like i expected...

Anyone else experience this? I have stock cats/manifolds. Love the tone but i feel like when I hit WOT it should get progressively louder as the RPMs climb....
Ive had many muscle cars with a variety of exhausts and never experienced this.

Also- I doubt the exhaust tips affected the sound greatly- but i put corsa clone style quad tips on it.

I appreciate any feedback. Thanks guys!!

_Justin

Nathan C

Headers would make it sound louder but the exhaust tips could play a factor also. Both my cars have SLP LoudMouth 1 but my Formula has the factory tips welded back on and sounds louder than my TA with the SLP tips.

udienow

iTrader: (18)

Strange for it to get quieter... but as above poster said long tube headers should wake it up. However, if you really want it loud, the simplest and cheapest solution would be an electronic (or manual) cut-out. I have one on an otherwise stock engine and it is VERY loud at WOT. Almost too loud as it makes your car sound like all bark no bite.

BrntWS6

iTrader: (7)

Headers will completely change the sound so much you may not like it. It's also loud as hell at wot with headers. I ended up ripping it all out and going tds after I did HC, it was just too much.

Jray68

Thank you for the feedback guys. An E cutout is a great suggestion, I was considering that but do not want any chance of an exhaust leak sound when the cutout is closed, are there any cutouts that don't leak?
And i appreciate the heads up on headers changing the note- from what i have been reading they completely alter the sound of the GMMG, and to get rid of the rasp a lot of money has to be spent in resonators/ hi-flow cats etc... not something im wanting to do right now.
I may go the E cutout route if i can find one that doesnt leak. Thanks again!

udienow

iTrader: (18)

http://www.dmhperformance.com/ecutout.htm

That is what is on my car. The 3 inch one. I had one on for 4+ years and I just within the past month or 2 had to replace it because it starting rattling/falling apart. Never leaked when closed. I haven't tried any others, but from research I did 4+ years ago, this was the best brand to get. I assume the same is still true today.

I highly suggest adding the cutout here:


Right after the Y merge, basically behind the passanger seat, there is a nice indent where the cutout fits perfectly without really costing you ground clearance.

Edit:
Here is a pic I found on google of it installed:

Jray68

Thank you for the recommendation on that cutout, looks like the one i'll go with!
Question- has anyone noticed a difference in exhaust tone with the cutout closed? Of course the Y to the closed cut out adds some restriction/turbulence to the system, and im wondering if this affects the tone/sound...even a little? Thanks again guys

udienow

iTrader: (18)

I don't see how you would get any sort of tone/sound difference with the cutout closed. When closed the exhaust flows out the back through the muffler as it does on your car currently. It should sound exactly the same when cutout is closed.

If you want to change the exhaust note with the cutout closed, you are going to have to replace your headers and Y-pipe. There are tons of options on this ranging from just under $400 to well over $1,000. You will also gain some HP to boot!

Jray68

Ok that's good to know, I'm pretty **** and notice small changes like that, so that was my reason for asking about the possible tone change.
Sounds like that cutout is exactly what i'm looking for, thanks for the help!