Ya, with the turbos so low and the high oil psi that mod motors make, especially with aftermarket pumps, both the restrictors and the return pumps are needed. I know the Hellion cars we've done, if you don't put the restrictors in, they smoke after you are into boost with them on decel.I do know what alot of turbo cars have to add restrictors in their lines as well as add a pump to help the oil flow..does this have something to do with the positioning?