Well on ebay it says the K2 gives you 30HP, so a filter must and new exhaust must net you 60HP easily
Easily, its a running joke between me and another guy on there, me comparing my old 350z to his car
Jerry i was running 40mm on the rear, for just over a year, never had no issue's at all, but then again never set the car up for track use, the Zed is a strong bit of kit, Phil told me about that he was running 50mm and had no problems just make sure the hub-centric and you get them checked at each service and you will be fine bud