IF DONE by a professional, porting cylinder heads is an expensive business due to the many hours of work involved. But with basic cutters and grinding stones, plus either an air or electric die-grinder with a 6mm chuck, all you need is know-how, a good pair of protective goggles, and patience to do it all yourself.
Although tungsten carbide cutters are expensive, they really are quick at chewing through cast iron and aluminium. For combustion chamber work, a combination of a TC cutter and a flathead grinding stone