i agree, the 2 1/2" is plenty for even a modded v8. and thats the size all the mufflers are made for. its allready over kill for the v6. the y pipe is 2 1/4 on each side and steps up to the 2 1/2. so thats what you are after anyway. with my h pipe when i cut the y, the h was made to fit over the 2 1/4, then its 2 1/2 all the way to the mufflers. :shiny:i think stock is 2.5 inches.
i really wouldent go bigger than 2.5 anyways.