well to start off i ordered a set of rev flat face valves from a rev dealer. i was set xvt valves in place of revs. well after talking to rev many time i found out from rev that they make these valve for xtreme valve technology. i was told by rev that they are same quality as normal rev valves. i have used rev valves before and have loved them. well after believing rev i installed the on a fresh fully built $7000 typer motor. 200 miles i on break in a head of a valve broke off and now the motor is a paper weight. from the valve breaking the head is gone the endyn piston has a 1inch buy 2inch hole in the piston and from the valve parts jumping from cylinder to cylinder it crack the cleave on cylinder 1. i do not recommend xvt valves and very mad at :gunleft: rev for saying they where great valves. rev is trying to blame it on something else. do u believe they wanted me to send the the whole head with cams and all. they wanted to check the cam lobes and valve springs what a bunch of crap. :wtf: