I've got a true dual exhaust, 2.5" back from Hooker shorty headers into an X-pipe crossover and two catalytic converters in the space where the original single cat was. Two exhaust pipes run down on either side of the driveshaft, and then travel through the panhard rod area over the rear axle. But I had Thrush super turbo mufflers squeezed under there, and they hung kind of low and now have holes from the scaping. I never liked how they were installed, they weren't tucked in well. But there's almost no room for decent mufflers under this car. There would be if the spare tire carrier was cut out and blocked off.

But without extensive modification like that, the best idea I could come up with was 5th gen (C5) Corvette mufflers. They have a 2.5" inlet and twin outlet on the same side. It's good for compact applications like this. Except that on the Corvette, the exhaust is a center dump. The only way to fit them in the space where the original single muffler goes on the IROC is to mount them upside down so that they dump out to the side.

The only problem I see is having both exhaust pipes come through where the original single exhaust passes. Although they're already there, it's a very clumsy routing in my opinion, but one of the few paths the dual exhaust could pass around the rear axle. One friend of mine has their exhaust dump in front of the rear wheels so that they don't have to mess with the axle, but without much room for mufflers, he has a volume problem. He's just got cats and no mufflers. It's obnoxiously loud.

The only problem I see is unequal length, between exhaust pipes feeding into the left and right mufflers. If I stick with mandrel bends though, the effect might be minimal.

I'm going to drop off the IROC to have the exhaust modified (again!) for these Vette mufflers I bought. ($100 for a used pair, from a brand new C5 that someone bought a Borla system for at only 2500 miles on the odometer).

Does anybody have any other advice for getting around the rear axle? Will it fit any other way other than through the path the original single exhaust passes?

Thanks.

 

if it works, that u can mount C5 mufflers underneath there, i want to get a LS1 and corsa system for my car!!! LOL love that sound

 

I dropped the car off yesterday to get it done. It should work fine. But the Corvette mufflers need to be mounted upside down to fit...I guess the C5 Corvette is substantially wider than a thirdgen F-body and there isn't enough room to mount those mufflers right side up to have a center dump exhaust. So a little bit of cutting and welding is still required to fit them to the F-body...but I see no reason why you couldn't put an LS-1 and Corsa C5 mufflers into your F-body.

Hot Rod magazine I think it was, did that recently. Within the past year anyway. They had to drop the front crossmember and cut and weld up a notch to fit the LS-1's A/C compressor. And the mounts were different. You'll have to use the 4th gen's LS-1 drivetrain though, because they have the transmission mounted to the back of the engine conventionally. Corvettes have the transmission in the back of the car.

From what I understand, it makes the third gen really nice driving, and quick. Plus who wouldn't love that double overdrive transmission. Imagine getting 30 mpg and picking up all that performance too.
That's a really good idea.

 

Dropping the car off Sunday evening should not have been a problem if the exhaust guy came in to work at 7 AM Monday like he should have. But he was sick at home with the flu a couple of days, during which my car sat outside in a neighborhood I don't entirely trust. By the time he came in, vandals had gotten to my IROC and it looks like they drove by and smashed the driver's side mirror with a hammer. I'm pissed, and I don't know if those parts are still available.

 

that sucks.

 

holy lord.. will his insurance cover it?