Well, I tried the BLP discharge nozzle on Vixen's QFT 450 today. For almost four hours. No amount of dickin with it resulted in any fuel being discharged. Nothing. I tried everything. Clearing the four discharge holes with a very small drill bit...small enough to insert by hand and remove no metal. I tried no lower gasket and with the lower gasket. I even tried making the chamfer on the bottom side just a tad bigger thinking it wasn't enough to allow fuel to flow past the screw. Nothing. After four agonizing hours with my back bent the hell over, I gave up and put the old QFT/Holley style nozzle back on. Small amount of money spent, but big disappointment. I cannot recommend them.