and oil lines\restrictor goes like this. I ran an open -4 line to my BB 700 turbos and I also noticed this restrictor built into the turbo and figured it didn't need anything more. I drove the car around for some time until it would smoke like crazy. It smoked just cruising it around, some members can remember it smoking at the track as well. Clouds of smoke. Couldn't figure it out. I took it upon myself to do some research and found that it seemed the turbos needed some sort of external restrictor built into the oil feed line. Long story short.....installed the restrictors and the car hasn't smoked any more. Makes sense to me why HKS does it.