Hey i want to know whats the expected stock boost for a 6gc gt4. I was told its about 11-12 psi but mines at stock peeks a 14psi with out a boost controller. If its suppose to be 11-12 psi is it good or bad that mines goes to 14 psi stock? and what is the maximum boost that 6gc gt4 can take on stock pistons if i want to upgrade?

Also air pressure in the wheels how much air is good for launch when racing. Do you put the full 30 pounds of air or would it be better if there is less air in the tires?

14psi on a gt4 is normal stock boost on your car. You can run that all day long.
If you want to crack it up higher, you could try for about 15-16psi. Above that, you hit fuel cut at about 17-18psi.

Just keep in mind that every car is different. It wouldnt be a bad idea to do a few dyno runs, to see if your car is happy with the boost you have it set at or the boost you want to turn it up to.

Lagos is right about the stock boost. Depending on air temp and a few other factors, stock "high" boost for the ST205 is 12-14psi. I normally saw 13-14psi before putting on my boost controller.

As for drag racing and tire pressures, that all depends on what tires - and this forum probably isn't the best place to get good answers for that. Just try out a few different pressures. (though, I have often heard that street tires work best around 20-25psi for drag racing)

-Charlie