in order to put a 5" turbo back exhaust (if posible) do I have to modify the firewall or any area of the floor pan. thank you.

 

negative...

 

short and sweet. thank you

 

No my 5' exhaust came with a 4 inch downpipe, I think most of the kits come with a 4 inch down pipe, may be wrong though, but I gave 300 bux for my straight pipe 5 incher off of ebay, the downpipe may be a tight fit but it goes in pretty easy. And oh man the 5 inch system is so freakin loud when rip into it, sound great.

 

The 5" exhaust systems come with a 4" downpipe