I run a WS7iii and its awsome, got a JP1 pipe on it and it gives great torque and loads of top end. I know some one who has C6 with a JP2 and it rips. he is the top contender in my area. I have jeard the JP3 is great, gives both top and bottem end power. But both are good engines, whatever you choose from RB you won't be disappointed