Deciding on an exhuast

[Mario]

To keep the sleeper effect on my new GLH, I was thinking of running a 3" DP with a 3" cutout, and having a pipe that tapers from 3" to 2.5" to merge the current 2.5" Exhaust that's on it out back. Think this will be too restrictive/waste of my time? I have a full 3" exhaust with a dynomax straight thru that I could throw on there too...just kicking around the other idea.

[Whorse]

I personally like that idea a lot. I like the look of a near stock exhaust with a cutout for limited use.

[cordes]

I thought about doing something like that, but decided that the TU 3" was so inexpensive that I could not pass it up. Also, I figure that I would be too lazy to get under the car and close/open the cutout. An electric one would be a must for me.

[Whorse]

Mopar_Nutz ran one when I was up there, and the in-car switch is one of hte coolest things I've seen in a car.

[Mario]

Yeah, I have an electric one. Pretty nice unit. I have a cutout adapter flange for it too. It's a stubby piece but goes from the 3" Cutout quickly to a 3.5" cutout and that's the size my electric cut-out is.

[Speedeuphoria]

look at the 2nd graph it is basically what your talking about. This is a dyno of 3" then to 2.5" catback on a stockish SRT4, then the full 3" made like 3 hp more, but w/ a cutout you would loose nothing
http://maxxfab.com/welcome.html

[8valves]

Just so long as the pipe prioritizes the cutout when it's open. As in, at the Y junction the straight portion is where the cutout is, and the offshoot bend goes to the rest of the exhaust. It's more work, but it'll be way better.

Back when my car was S60'd I had a 3" SV to 3" DP to a electric cutout, then down to totally stock exhaust from there back. It was sweet, and it got loud, but even with the cutout open I could still feel exhaust through the muffler at IDLE... imagine when velocity in the pipe gets up there under WOT.

Dropping the rear exhaust at the track picked up 3-4 MPH. I know this is an extreme case since you would do 2.5 and this was 1 7/8 out back, but it shows that placement of the cutout is more crucial than you might think.

[contraption22]

look at the 2nd graph it is basically what your talking about. This is a dyno of 3" then to 2.5" catback on a stockish SRT4, then the full 3" made like 3 hp more, but w/ a cutout you would loose nothing
http://maxxfab.com/welcome.html

Yeah but the turbo itself is so restrictive on an SRT-4, what's behind it doesn't seem to make much difference.

[Speedeuphoria]

Yeah but the turbo itself is so restrictive on an SRT-4, what's behind it doesn't seem to make much difference.

totally agree and they also dont show the a/f so it could have been gained there as well and they do sell 3" exhaust so they could be biased

[GLHNSLHT2]

the 3" exhaust on my Daytona is a lot more stealthy than the 2.5" was. The 3" is a nice deep smooth tone where the 2.5" was loud and crackly. And with TU's kit so nice and cheap you can't go wrong. Go full 3" with a nice race magnum dynomax out the back and you'll love it.

[Mario]

I already have both complete systems. I know what both sound like. I just was toying with an idea and was wondering if anyone had any experience or insight on such a set-up. My 2.5" Exhaust I have has a grandma muffler on it and thought it might be a fun idea.

I wasn't asking the difference in sound and I don't care if Joe Blow charges $50 for a full 3" and Hot Rod Harry charges $500. I was asking more about the idea of a 3" exhuast, going to a cutout, merging to a 2.5" exhaust and it's restrictiveness.

[8valves]

Did you read my post then Mario?

[Mario]

Yes, I did. Thanks man. I just got a little worked up for some reason over a different post.

Thanks to all that responded.

[GLHNSLHT2]

what I was saying is the 3" is more stealthy than the 2.5" when it comes to sound. And no restriction issues. If you have a full 3" with the dynomax throw it on.

[Marcus86GLHS]

if you have a well made full 3" system (no cat. convertor) and a low restriction muffler the cut-out will really offer little or no appreciable power gain.

on an omni, keep a turn-down on the end of the tailpipe (like stock), thats a good way to keep it stealthy.

[puppet]

One thing I've wondered about is if the is any "special" tuning involved with a cut-out/stock combination? In other words does the engine react differently enough to one or the other (cut-out vs stock mode) to have a big effect on performance/economy? ... big enough to goof up a good tune for one or the other?

[BadAssPerformance]

That would probably depend on how much the car is built. My "stock" '87 T2 shadow runs the same 13.00's @ 104-105 mph on the open 2.25" DP or full 3" with oval muffler, no cat. Everything else other than the exhaust the same.

[SQUIRRELMASTER]

2.5"downpipe 3" full exhaust with a dual outlet muffler this keeps the look comming out the back less agressive, but with 2 outlets you aren't downsizing the pipe anywhere... If you are looking for all out optimum flow. Cutouts are nice, but leak where the flange butterfly swivles... I have installed quite a few...

http://i30.photobucket.com/albums/c3...glhscutout.jpg