I upgraded my recently upgraded single T88 turbo on my street legal 01' Skyline GT-R NURII V to twin T78 turbos(each at 15.5psi) off a BNR34 block with a GREX Forged Piston set(not all modifications), but after 320KPH (est.190MPH) it doesn't have the throttle response or the balls that the single T88 turbo I had, given I used 150cc smaller injectors, but it didn't loose any bottom end power at all. 680hp. (730hp maxboost)