My 2001 GT has 105,000 miles on it and is need need of new mufflers. I plan on replacing the whole cat back system as the resonator is pretty rusted and will most likely eventually go as well.

Here is the problem and question. My stock GP has mandrel bent pipes. I plan on replacing everything with Walker OEM parts but the bends are not mandrel they are the bent bends with the ridges. Will this make a difference in performance? Should I even worry about this?

Also, Advance Auto's website says the Walker part fits but does not give the inside or outside diameter of the pipe. Does anyone know the diameter? Part #55204 I need to buy clamps for all the pieces as I intend to do the work myself and do not have a welder or even know how to use one.

Thanks.