yes i was wondering if anyone could tell me how much psi the greddy turbo (TD05H-18G) for a 99-00 civic si is capable of making????

Its somewhere about 7 to maybe 21 but I think the most your going to get out of it is 14 psi without modifiying the turbo.

what exactly do u mean by modifying the turbo do u mean like new housing and or cartridge ???

Could a Honda V-tech handle 21psi without modification? I doubt it.

Yeah like changing the housing and turbine and getting a boost controller. But if it is a stock engine i would only run 7 psi never higher. Besides that turbo is the one they used on the turbo eclipse. But i would first get some forged pistons and maybe some turbo cams before i bought a turbo kit.

I don't know about psi, but I know that kit will support anywhere from 350-400hp. But like pippip said, if you plan on really boosting, get some lower compression pistons along with rods while you are at it. Also, port the head and get new valves, springs and retainers. This will free up some extra hp.