Anyone ever used these to solve base gasket leak on an Evo?

http://www.jpcycles.com/product/423-005

I have heard good reviews of them.... I hold to the school of thought that if your cases and cylinder bases are properly flat then your not going to have issues either.

ive been looking in to these too thay have good reveiws the secret part is sopose to be the brass jet bit the gaskets are james apprantley, but i think it would be wise to face the base of the barrels to, strange though last time i asked a machine shop in perth to do a set thay said thay never have in 25years of doing harley stuff but thay will be soon , as mine still has a leak and thats with the james silcon gaskets but i will be putting in new studs this too for full refreash top and bottom have two evos to do  $39.90 from phat performance  never brought from them before though

Thanks guys for all your replies will take it all on board.
I was told main reason they go is rev them to hard when cold yet knew a dealer in Tassie and he never had a problem with his and he never warmed it up yet Dave his offsider if he ever didn't warm it up first and just gave it to it he would blow one every time