[Markgase2000]

This is what i suggest.
Go to a minute muffler , tell them to remove the catylitic converter , resonator and muffler. If you dont want your Check Engine Soon light to stay on then keep the catylitic converter on , if you dont want it you will have to buy a module to bypass it. This device is called O2 Simulator. The muffler shop will replace your cat with pipe and if you want to have dual bottles inline use a higher bore blue bottle , example: from 2 1/4inch pipe to 2 1/2inch bore to 2 1/4inch pipe and then they replace your muffler with a blue bottle and put any tip you want on it. If your GT has a catback system and you want duals just double what i suggested should work fine. But I will warn you , its VERY LOUD , easy to get tickets and it sets off car alarms. It costed me around $300 to get it done for me.(canadian) Also i used the baffle kind of blue bottles reversed.