I agree with Jerry, the pusher fan is not going to help, and in fact will impede air flow. The 15# pressure cap will not help keep things cooler - it will simply boost your sustainable peak temperature higher to prevent boiling. You need to be sure that the specific Walker radiator you have is designed to handle 15psig pressure - they have some that call for the 7# cap, I believe. Are your two puller fans mounted to a shroud panel, to force all flow through the fans?