I'm thinking of upgrading my exhaust system on my 94' Z28.
what would give me more HP and torque the y pipe system or true dual?

 

I would say a y-pipe, unless you're running over 400 rwhp. Plus y-pipes sound nicer than X-pipes... imo.

 

Duals would give you more power but they are noisy and can get tiresome after some time. I went to a mufflex 4" system with a y pipe but i have 2 cut outs after each header if I ever feel the need to open it up.

 

how much more hp could I got from removing my cat when I do my exhaust upgrades ?