not making boost, help

[OnlyNeed4]

ok, i bought a 90 talon tsi awd about 5 days ago and it is not running at full boost, the most i can get is 8 psi, full throttle, and it takes until almost redline to reach 8 psi. I took off the intercooler and cleaned that all out, new air filter, plugs, wires, basic tune-up stuff. I am just wondering if it is the turbo, since it is stock with 112,000 miles, or what. And also i want to rebuild the motor with pistons, rings, head. But i dont know what all i would need. Can i just use 2g pistons and rings, and i found some cylinder heads on this site for like $300-$500, can i just use them? I also plan on buying a 16g turbo and full 3" exhaust and bla bla.
I was just wondering if anyone can tell me if there is anyway to gain boost back on my stock turbo until i get the new one, and if rebuilding it with the pistons and head i said would work. Would i have to bore it over or what? I dont know much about dsm's, this is my first one. Also, if i get a big 16g turbo, will it be a direct bolt on? does it come with a new wastegate? Please leave anything that would be helpful. thanks for any help

 

[CanadianTSi]

You probably have big cracks in either your exhaust manifold or turbo or both.

 

[slowpokin699]

why do you want to rebuild the motor? i would hold off on the rebuiuld till the motor goes. the guy before me was right about the turbo and or manifold. time for a 14b or 16g.