[justjames80]

You want to pay most of the attention to the downpipe. If the turbo you have is running something like a 4" V-band then try to have a smooth 4" downpipe at least until the bottom of the firewall. After that you can go down to 3" plumbing with mufflers. Don't let anyone tell you that mufflers or dual 3" plumbing is too small and will cause backpressure issues. They are wrong and I know of a 8-sec turbo Mustang with full exhaust that would prove it. Keep the bends smooth and use a set of quality mufflers so you don't annoy everyone you pass by.