If you don't put better rods in it you won't be able to rev it to where it can make some power,The stock rod are probably good for about 4500 RPM and you will need to run it almost twice that high to get some power out of it,more compression makes more power too so you should mill the heads,then you will need a better camshaft too.The 23 HP heads are some of the best flowing but they need porting and better valves springs and retainers.The stock rocker arms are not much good for racing either