Which size exhaust to go with?
Theres 3 inch systems on the market from Jegs, Sumitt and Pypes. Probably others as well. But they come to mind first.
Anyway.... depending on HP level, a 2-1/2 will handle most engines well and do it quiter. There is an advantage to a 3 inch pipe @ around the 450 HP level. But it is small. It really shines @ 500 HP+, where it will really show.
The biggest issue in exhaust is; mandrel bent pipes, constant diameter in the muffler and if you have the coin to do a "X" pipe system, it would be well worth your time to do so.
It does get tight no matter the car body style.