Is there a chance that the fuel map for your existing engine are too lean?
Getting a piggy back unit for the ecm might be a good idea so that you can be sure the engine is not starving with the way it is set up now.
Are you unhappy with the low end or top end?
If it is the low end, then maybe you went too big on the exhaust system.
Try the Summit Racing tech line, they will give you better help then most of us can.