I've heard good things about this but what exactly is it? How well would it work on my 250X? Also about how much does a job like this cost? Thanks

 

I am not sure of the cost.But what they do is grind away the at the top of the valve and make it shaped kind like a trianlge on it's side.this alaows for fuel in or exhaust without getting bigger valves.It is supposed to help alot i don't know from first hand experience though.

 

You will never know it was done. It just makes the valves seal better

 

It's just the method they use when refacing the valves and valve seats. Absolutely do not pull your engine apart to do this, you won't gain a thing. It's just the standard valve job done when reworking a cylinder head.