Battlegun is spot on for the work necessary to increase the performance level 2-3 more HP. As for exhaust manufacturers, This depends on what you want your bike to sound like. HMF pipes are generally fairly loud. LRD are somewhat docile. I am partial to Two Brothers myself. Visit the manufacturers websites, see if they have db (decibel) readings of the systems and compare those to what stock usually runs at (85 db). That will give you some indication as to how loud it will be.