I have a 1991 Z-28 with an L98 and just have a few questions.

The first question isn't a major issue, just something I'm curious about. Does the stock routing for the exhaust go over the rear axle? It looks as if someone on my car just replaced it with a straight pipe from where it bends towards the back, all the way to the muffler inlet elbow.

My main question: My car has the stock dual cat option, and I was curious if the location of the cats are the same as on a single-cat car, because I am looking at buying a cat-back exhaust, but am not sure if the cat-back systems manufactured would be a direct bolt-up to the dual-cat cars.

3rd question is, would there be any noticeable performance increase over the stock dual-cat system if I installed an after-market cat in their place?

 

Yes

A single cat cat-back won't be a direct bolt-up to a dual-cat car.

Most likely.