So Ill start off with saying that the car is a 1991 T/A GTA with the l98.
It has the factory dual cats/ y-pipe but an aftermarket 3in cat back single exit.

I'm looking into finishing off the exhaust with shorty headers and a y-pipe.

Ive searched all over and I think I have come to the conclusion that the Hooker 2055 and y-pipe combo will flow the best but it is a single cat system.

I am wondering if it is possible to do this without throwing a CEL since I emissions here. I believe there must be a way to do it but I have searched and come up with nothing.

I would assume that the Prom just needs to be re-programmed but can anyone help me please?

 

Search this Exhaust board for "Dyno Don headers" and look at the wonderful setup he sells for our cars.

Then send him (Dyno Don) a PM for more info.

Yes you can convert to single cat but you'll be giving up power if you do. 4 cylinders into two different cats is better than 8 cylinders into one cat.

 

Ive heard a lot about him but does he sell a dual cat y-pipe as well?

The only reason I was going toward the 2055 is that Ive heard great things about their y-pipe but if he makes one then great.

 

Yes he does. I just left his shop and he had a car on the lift which had a set of his headers. It had dual cats, and Don was about to weld in the y-pipe when I left.