I had a few questions about how to take my car to the next level...

My current set-up is a '97 GS with a Hahn stage 2 kit w/ FMIC, currently running 8psi.

?s
1) How much boost could i run with only upgrading my pistons & rods?
2) With only doing #1, is tuning software a must?
3) Is #1 worth it? or should i go all out at once and also do some BC 272's, ECMlink, Clutch, Flywheel, LSD, bigger injectors, etc?
4) Y did Hahn delete their stage 3-5 kits online? r they even available any more?
5) Is there anything in #3 that I missed for a pretty powerful car? 400+ hp?

Any and all feedback welcome,
Thanks,