I remember that thread, turned into a mess eventually. I would never pick up a car running high compression, stock internals and forced induction without a new tune after exhaust modifications had been added.

Aftermarket headers can't be used with GTM's stage 2 s/c kit. The compressor is so big that it won't fit with long tube headers, I'm not sure if you could modify the headers someway to still use them, it seems like Sam's general tone is that you should not be running long tubes with the SC kit. I think the single turbo setup done by another forum member completed by JTran Studio's uses the long tube headers with his single turbo setup. I love the headers, its a same there seem to be so many obstacles mating them with the quality S/C kits that are coming out for the z34.

Does the 9psi pulley require a new belt? My local shop is telling me no but want to confirm before ordering.

Nope.

Can you guys provide input on 9lb pulley vs 928 impeller upgrade? Planning to do one or the other (not both-stock motor). For the money and performance which would be the better option?

Either way, swap to topgunz's air to air setup if you want your motor to live.

Yeah, do both and make a lot more power, safely. You have already made a big investment for a supercharged car. Add a fraction of that more into it and make some serious power.