If you port a supercharger and your boost goes down, something went very wrong.
OP I would run a 3.5, in my experience .1 bigger on the pulley was good for eliminating 3-4 degrees of KR.
What would really help is a full tune, but since you don't have access to that playing with other stuff is pretty much your only option.
Depending on how much boost you're seeing on the 3.4 it'll probably get worse come cold weather. For example if you're already seeing 11-12psi... Theres a goldie locks zone that the m90 likes to be in and weather brings it to both extremes with changes in season.
