I left the transmission gearing alone, only renewed the clutch pack. The clutch pack is supposed to handle power in the 100hp range, right where the ZR600 comes in at. I used the same clutches from the ZR setup, just switched to a slightly shorter belt so I could have the engine closer to the transmission. The engine drops into factory bolt locations, only minor alterations were made (battery, and rad relocated, and ZR ECU mount)