just wondering at what psi does a stock series 5 turbo run out of effiency with and without a FMIC???.

 

I think he means the turbo itself... assuming appropriate other mods.

 

I think efficency stops around 18 psi, after that the turbo spools to fast and will breake, but the fuelsystem is due to stall much earlier, even if you upgade with bigger fuelpump, injecotrs and some kind of ecu (S-AFC or remapped) i would NEVER boost more than 15 psi. Better to be safe than sorry! :-)

///kelimutu

 

I believe 12 psi!!