Anybody go from performer to an rpm air gap

Good to know. I've always assumed that it was for static balance between runners @ high RPM, to gain cylinder sharing at high runner speeds.

Do you know what your distributor advance curve numbers look like, Sam? It would be nice to see what kind of advance you are getting at different RPM ranges. Stock springs don't give full advance until some unreasonable RPM, which could be killing top end, as well. What RPM does it start to taper off at?