I got mine at work.........The Home Depot. They held up remarkably well during the whole process with the intake, still trying to figure out how I'm gonna attack the heads.

 

The only reason why i dont like mounted stones is for the simple fact is they should be used to finish off the runners for a semi-smooth finish on the walls .

The other reason why i dont like using them is they change shape after using them and you have to keep re-dressing the stone but its never the same size and shape after that.

I use the long carbide burrs for the port shapping and the 6" long burrs to get deep into the intakes or heads.