i have the 520 conversion kit on mine. not that big of gains in torque/low end power. does make it a pain on the highway. get annoying screaming at 6-7 rpms going 65-70. i bought the sprocket specialist superlight chain kit.i bought it mainly cause i was going to buy a new gold chain and black sprockets. if you dont do a lot of highway riding, go for it. corey at mummy is great to work with. get your gdc discount. the bike will wheelie with ease stock. dont be afraid to twist the throttle or dump it