Maybe its just me, but the only fuel screw I've had any good luck with is JD Jetting brass fuel screw. I've tried Tusk, DB and ZipTy (the aluminum Zipty tip actually broke off inside the idle circuit which was extremely aggravating. I just tried installing a titanium DB into my 07 FCR 450 carb and it would not seat properly into the full lean position. Needless to say, I will be putting JD scews on all my carbs. Has anybody had different luck?