Posted 28 July 2012 - 02:53 AM
If the faction valves are stainless steel valves, it's fine to lap them in. You won't need to replace the seats if you check them after you lap them in and they don't leak. The seats are more durable than most people thing. It's the stock valve that takes most of the beating, but the seats can too so make sure that after you install the new valves, you dump something into the port like cheap rubbing alcohol and see if they leak. Sometimes they will leak or seap a little. As long as it doesn't start pouring out immediately, they will usually beat themselves in.
I've used faction stainless valves in the past and I've had a few broken valves springs do some damage. Faction was good about replacing the broken springs, but they didn't cover the piston that got taken out when it happened to one of them.