there two schools of thought on the pressure tap location, one is to locate it at the largest diameter of the divergent cone, the other is near the exhaust port, one can see this done on many ops.rossi, and picco headers, as well as the nelsons and jett tuned mufflers. i suspect if your setup is leaning out at the top of a loop, that your needle is set too lean, or your plumbing on the tank is too small or has some restriction, or your pipe is a little short... FWIW, pulling the pipe back a .250 inch and backing the needle off 2-3 clicks will probably fix this