Hey I finally got a dual exhaust system on my IROC.
I tried a single exhaust and I just wasn't happy with the sound. It didn't have that stereo rumble that I remembered of this 355 when I had it in my 68 Corvette. To me, it sounded flat.

What I had done up to that point was to install a pair of Hooker Competition headers and my own custom high-flow Y-pipe into a 3" Catco cat and out through a stock muffler.

What I did different to make the dual exhaust work was to convert the Flowmaster Y-pipe into an X-pipe crossover, and then had two Catco cats installed side by side in the stock catalytic converter pocket, with the AIR tube inlets joined together. Then I took two 2 1/2" pipes out of the cats, right down the driveshaft tunnel. I put one Thrush Superturbo muffler under the car, tucked as high as I could, in a little space that was there. It now sits about 3 1/2" off the ground. Then I put the second Superturbo muffler where the stock muffler goes. And two pipes sitting side by side snake up over the axle and through the panhard rod in the same path that a stock 3" pipe takes.

And then of course, one pipe goes straight out back and the other pipe goes through that muffler in the stock location and straight out the other side.

True dual exhaust. And it sounds good. Nice stereophonic idle with my rumpity rump Isky cam.
How does it feel? Good. Can't really tell that much of a difference by the seat of my pants. There is some though. I used to not peel out too easily with the fatter tires I put out back, unless I really stood on the gas. Now, everytime I romp on it, I break traction. So yeah, I guess the power is better.

Super Turbo mufflers are real quiet at cruise. In fact, the whine of the tires on the pavement is the only thing I hear. But get on it, and the mufflers sound out, and sound pretty good.
I would've liked more exhaust note, but my wife doesn't. She thinks it's perfect.

 

Pictures or sound files?!

 

Yeah, able to get any?

 

No pics or sound files...yet. I just did it Saturday.

These cars are really a challenge to dual exhaust, mostly because of how low to the ground they are.

Unless someone decided to run Dynomax chrome sidepipes or something. I guess you could do that. Exit out of the cats and go straight out the side.

Lots of burned legs though.

 

And lots of dirty looks.

 

what are the specs on that isky cam?

 

no wonder it sounded flat

 

Yes, I'm sure the stock muffler was to blame. But I didn't want to spend the cash on a cat-back single if what I ultimately wanted was a dual. The single sure would be easier on this car, BUT it is possible to dual exhaust these things, just not easy.

By the way, the cam specs I accidentally posted as a new topic. Sorry. It's an Iskendarian cam with around 270 degrees total advertised duration.
The 0.05" duration is 221 degrees, intake and exhaust, with 0.465" lift, intake and exhaust.

So you see, with the same exhaust grind as intake, I really needed a good exhaust system to make this cam work. And it does work nicely.

The other day a C5 Corvette tried to show off in front of me, and the harder he accelerated, the harder I did. I really played with him and didn't even go full throttle. He couldn't lose me. At the next light, I ignored him, and he peeled out and made a spectacle of himself...all by himself. But I'd already proved my point.