Well I took the regulator piston out tonight and shimmed the spring with a couple of washers, about 1/8" total - much better at idle, did not take it out on the road yet though. BTW: I'm running a lot of caster, which will make the pump work harder when the car is stopped or at very low speeds.
Rod, that piston did not have the limiting shaft or whatever.
MK3 IRS 347 Comp XFI 236HR-14, AFR 185s, Vic Jr, Bigs Stage 5 750 CFM N20, Pertronics HEI, Levy T5, 3.73s, Cobra brakes. Coupe under construction!