3" to dual 2.5" Exhaust?

[MichBC3]

I have a 3" downpipe on my 87 GN and would like to split it into dual 2-1/2" pipes at the cat flange to make the rest of the exhaust sytem easier to fit - especially over the axle. Using 3" pipe past the split is unnecessary and creates body and suspension clearance problems. Does anybody make a 3" to dual 2-1/2" splitter assembly?

If not, does anyone sell separately a 3" inlet to dual 3" pipe splitter part (not an entire exhaust) like used in the Magnaflow 16884 system? I'm thinking I could reduce the dual 3" outlets to 2.5 before hitting the mufflers.

 

[0-60n4]

My comment for consideration only: Many people prefer the look of a dual set up. As far as performance, comparing the flow and weight difference, a single 3" is better. One option on the single 3" is to just have it turn down just past the muffler, before the axle, instead of going all the way back. That is how I have mine.

 

[Nick Micale]

The Pypes dual exhaust system comes in 2 sizes for a GN, 2-1/2" or 3".

The 3" system clears the axles and frame easily, and both systems exit like the stock system, but a LOT less restrictive.

Neither system has any annoying drone, but I prefer the 3" kit for a modified, performance engine!

My 3" system also has a Pypes electric cutout that takes me back many years to my "fun" street days!

 

[MichBC3]

My comment for consideration only: Many people prefer the look of a dual set up. As far as performance, comparing the flow and weight difference, a single 3" is better. One option on the single 3" is to just have it turn down just past the muffler, before the axle, instead of going all the way back. That is how I have mine.

Thanks, but I have that (single muffler 3" under the car with shorty pipe before the axle) setup now - using a magnaflow. Too boomy for my liking. Need to get that sound over the axle and out the back. I don't care about the looks of a dual setup, but if I had 2-1/2" duals, they'd be somewhat quiet and wouldn't restrict the flow of the 3" downpipe.

But thanks for taking the time to respond.

 

[MichBC3]

The Pypes dual exhaust system comes in 2 sizes for a GN, 2-1/2" or 3".

The 3" system clears the axles and frame easily, and both systems exit like the stock system, but a LOT less restrictive.

Neither system has any annoying drone, but I prefer the 3" kit for a modified, performance engine!

My 3" system also has a Pypes electric cutout that takes me back many years to my "fun" street days!

I've been looking at the 3" Pypes system, but the local muffler shop says that the aftermarket upper control arm and my sway bar probably won't clear a 3". I figure a dual 2-1/2" system past the 3" downpipe would be a bit quieter anyway. Perhaps I'll just have to try the SGG51R and return it if it won't clear.

 

[MichBC3]

By the way, just to eliminate possible confusion, in this thread we're talking about my newest acquisition: 87 GN. I still have the TTA but haven't updated my profile.

 

[1986 Buick GX1]

Thanks, but I have that (single muffler 3" under the car with shorty pipe before the axle) setup now - using a magnaflow. Too boomy for my liking.

If you like your system otherwise, I would replace the Magna drone muffler a Hooker Maxflow muffler for a little quieter, deeper toned sound with no drone and gain a couple hp as a bonus.
You might try the Hooker VR304 (S.S. version).

Every Magna flow muffler I've tried had some degree of drone.
Over priced, over marketed mufflers, if you ask me.

 

[1986 Buick GX1]

Maybe you can post up what upper control arms and what sway bar you're running, I'm sure someone on here has been there, done that and can shed some light on your situation.

 

[NY Twin Turbo]

I'm a little confused.

So your looking for a 2-1/2 exhaust that bolts up behind a 3 inch downpipe? Don't all the good aftermarket exhausts do this? What's the problem?

Also, I can't see how a 3 inch won't work. Even with an upper Wolfe style bar. A 3 inch exhaust should be able to be made to work. It may require that the installer do a little more tweeking and adjusting before welding and/or tightening it up. But it likely can be made to fit. .

I used to have a 3.5 inch single shot over the axle with an upper Wolfe bar. It was tight, and on rare occasions, I would hear a "clink". But the exhaust wasn't damaged, Just a little kiss mark. For single turbo applications this is the best exhaust in my opinion!

But this is New York. In the springtime, our smoothest roads are like mountain hiking trails!

 

[pacecarta]

wolf style sucks but you can cut and refit (rotate) the tails to work , upper arms shouldn't be an issue ..stock upper arms are the worst for space anything aftermarket gives more room. on one gn1 3" dual i did it was a little close with an hr rear sway bar but the exhaust y pipe can be brought in tighter to get room to fit
on my 86 i have a 2.5" catback and has worked fine to 140mph well into 9s, there was no issue getting an atr 3" dual to fit with the hr bar and baseline upper control relocate setup .. now with trz rear swaybar i was told i would not be able to get the dual tails over axle to work , another thing that can be done for room is changing the stock springs for 2.5" coilover springs . this cleared enough to work the 2.5" tails over with minimal modification to the exhaust (cut and rotate)
on my other car i have wolfe bar and relocate uppers as well as coilovers and a 9: rear that also makes things a little tighter but with coilovers little easier becuase no springs on axle .. i did make a 3.5 single and after startup ripped it back out and put a 2.75" dual catback with magnaflows (old houston exhaust) again only mod was twisting the tails like i did in the pics ..this set ran 9.4's