gearing
The way sprockets work, for every 1 tooth in the front, equals about 2 teeth in the rear. So, going down 1 in the front plus going up to in the rear, it would be like going up 4-5 in the rear. Way too much unless doing wheelies is your goal. D.I.D., RK, Tsubaki and Regina are all good chains. Vortex sprockets are good but wear fast. There is one called Tri-metal that is also good. Changing the front will affect the drive shaft directly, and possibly your transmission. Actually, keep the front stock,(change though for a 520) try a rear with plus one, see how you like it, if you still need more, try a rear with plus two. It really is all about rider preference. just have to find what works best for you. Oh, if you do change out exhausts, do it right. Do a full system with a Power Commander(get the new PC 5), high flow air filter and ignition modual. A slip on, while getting ride of about 7-8lbs will only get about 2-4 hp.