Toyspeed

Hi Guys, I hope someone can help me out with this weird situation.

Its a 20v silver top 4age in a 1992 Levin. Only done 90000kms.

From cold start the car idles perfectly fine and runs fine doesn't miss at all.
Car warms up after a few minutes and still runs fine as long as you dont use ...

well all i want to do is get around 7psi of boost nothing to hurt the engine but with the high compression it has would a bigger head gasket do??

I want to put a turbo into my AE111 BZG and want to know what is involved how much it would cost is it worth it??

All help would be greatful