iv recently purchased a GT, it has the GT25R Turbo fitted in, my question is when should this turbo start kicking in, as it seems to be kicking in really late close to 4K revs, is this normal? or should it be earlier? secondly the previous owner seems to have left little to no room for any air intake, so has no air filter on the car, has simply meshed the turbo, and left it like that, could this be unhealthy? was thinking of creating my own air filter relocation and getting an air filter on their asap, anyone previously done that for these turbo's if so any measurements for the silicone pipes etc?