APAem1

When i took off my stock cat-back from my em1 i found the pipe was really small in diameter and also deformed. I was wondering, if i was to remove the piping from the b-pipe and replace it with a larger diamter pipe(lets say 2 / 2.25 inch) and remove the piping from the axle back and do the same thing, would this be ideal? Is the muffler free flowing enough for me to do this? I thought of this because i see people running stock itr muffler with 2.25 inch piping and said it was the greatest thing. I also didnt want a loud after market exhaust and low on money. What are your guys opinion on this?