hi all, i currently own a 2001 vrx magna,

i am looking at installing pacemaker extractors, a new cat and muffler, i have been recommended a strait flo 2.5 inch muffler, however i know factory vrx's hav a better muffler than the stock stock 3.5 already, could anyone give tell me if the new muffler would be of benifit, and also what level of power increase will i see with the extractors?