What does it do? I should know this...but I don't.

 

Exhaust cutout allows you to bypass the muffler or cats depending on where you put it. Cheap, effective, and loud mod. I love the sound on mine.



Looks like this when installed

 

They run around 30 bucks and are usually good for a several horsepower gain, maybe more in some cases. The spot right before the rear axle dump is the favored location to put it.

 

On my car it was good for something like 38rwhp over my flowmaster when I had a single exhaust, lol.

 

What kind of other mods were done to the car?

 

P&P heads, GM847 blah blah... lol.

 

They say the Flowmaster is restrictive and really shows when bigger mods are done, I guess your case is a prime example.

 

Can you use a cutout with a Magnaflow exhaust? Or does it give the same growl and hp gain w/o the magnaflow?

 

you can use it on any exhaust. find the size you need and slap it on there. simple as that. basically it makes your car alot louder. thats it

 

I'm sure you could, but i've heard the Magnaflow muffler is one of the least restrictive on the market "as a perf. muffler", thats what i'm running.

I'm hearing good things about cut-outs over here, but on another sight i got chewed out for even thinking about them, i personally don't see why they would hurt perf.

 

My buddies heads/cam LS1 car only picked up 5rwhp with his cutout over his magnaflow.

 

This is the route I went, not for the performance gain aspect, but the sound aspect. I bought a stainless steel cutout to have welded into the i-pipe portion of the catback since the catback is all stainless steel.