After reading Leo's book... he mentioned that for street use and not more than 6psi, factory cast pistons are ok.
panic~ I am using an eaton m90 with the high vacuum by-pass, as you said. All the reading I have done on these leads me to believe that boost will only build once the bypass valve closes... which only happens at around 3/4 throttle and up. As for the 5.5psi boost, everything I read on the 3800 performance forums say that the factory dia. pulley creates this amount. PLEASE, correct me if I am wrong... it has happened in the past (me being wrong)!
I have been in contact with Tlowe about a vacuum canister that will retard timing. I am not 100% clear on the operation of this unit, but I have spoken with another person who is using the same thing on a similar engine. He is very happy with it.
