The 5 angle radius Race valve job significantly raises the flow characteristics at low valve lift and definitely shows a horsepower increase throughout the useable power curve. The 5 angle valve job really shines on big valves as the seat diameter is opened up all the way into the aluminum casting, blending to the port work. Adding +1mm valves to a modified engine package helps the mid to top-end horsepower. Most aftermarket hi compression pistons are clearanced for +1mm valves.
