I just left mine alone and had great results. That was on a turbocharged 302/C4. The only time it was under boost was at 1/2 throttle and above anyway.

Once the mod. vacuum signal is gone, the trans reverts to using the governor and throttle valve for shift timing control. Doesn't matter whether it's a naturally aspirated engine or a boosted engine it works the same way.

Mine was 24 psi (the highest I ever ran it) and it always worked great.
[addsig]