As I said, was told they work ok w/a return but have more available volume deadheaded and this proves that point. I finally after many years of racing stepped up and got an "overkill" system and my et`s dropped and mph went up..............the $$$ difference bet. the Mallorys and holley blues and blacks isn`t THAT bad in my opinion and I have zero regrets. I too had 7 lbs. on my gauge but obviously had a "volume" issue having to jet up 8+ sizes just to get the a/f out of the death zone............not any more, now I`m leaning it down and TRYING to level out my fuel curve.