Different Fairing, exhaust,intake, and rear sets, and ditching the belt guards and inner fender as well. These things alone turn the bike into a different animal. As for the 515cc kit - I would go with Revolution Performances - though a hundred more in price, it is warranted, has a Wiseco piston - and mine has run 10 years with little to no compression loss - NHRS is a good place to find common parts, however, those iron sleeved cylinders with the CP piston - the skirt of which is too shallow and has issues - not a good long term choice as repeatedly shown on other boards. The Revolution kit is a good start on a long term performance Blast.
EZ