First up, you don't need air die grinders and carbide tips to do mild port work. The idea is to take out all the sharp edges in the ports and turn them into nice rounded edges (I'm talking about the inside walls of the ports - don't mess with the outer edges especially with the exhaust ports). Get the walls of the ports looking even. You won't need to take out great chunks of metal, just a little buzz here and there to smooth them out. I put up a post somewhere about how I tackled the porting on my 4G63 but I went a little (read as 'very') OCD porting my head and cleaning up the castings/previous bad repairs...