Picked up my cylinder head the other day. I had custom intake valves installed that are 1mm larger in diameter and the ports opened up a little to accommodate for the larger valves. Then when I ordered the custom ground camshaft, the company said that I would need to install double valve springs to keep the valves from floating or smacking the pistons. At the same time I would need new aluminum spring retainers to accommodate for the double springs. The new cam and springs will produce the best power range from 2800-6600 RPM, but it will rev to 7200. I am putting the rest of the engine together today and will let you know how it runs.
Custom ground
cam://static.mazdabscene.com/userphotos/2014/110/9176/l.jpg
New springs and aluminum
reta://static.mazdabscene.com/userphotos/2014/110/9178/l.jpg
New stainless v://static.mazdabscene.com/userphotos/2014/110/9180/l.