Alrighty so short and sweet. Just installed a garrett gt2871r in my 240. The previous t25 had no issues at all. In 3rd gear if i floor it i will hold about 5psi from 3k rpm and it wont begin to spool up more until around 4500, then full boost somewhere near 5k. Unhooked the wastegate vac line and it does the same thing. No abnormal noise or smoking coming from the turbo. Im tuned for the turbo and have all the appropriate mods. It runs great otherwise so im pretty sure i dont have any sort of boost leaks. And like i said the old t25 worked and spooled perfect before i swapped turbos. WTF!? looking for any suggestions before i shell out 300 for a rebuild

shaft play? where did the turbo come from, used/new?
what ecu?
pressure check system for leaks?
remove all the couplers and make sure there are no pressure cracks
how does the car run at idle? misfire, vacuum leaks?