So are you saying blackjacks are only as good as 38's if I remember right your a 550 guy and really you won't see alot of performance out of a 550 with any mods or atleast 8 months ago you were all about the 550's if your not downing the blackjacks then sorry about being definsive but this thread is kinda confusing maybe explain what you mean then but I'd have to say the blackjacks are the best running carbs I've ever ran the set I have even fell better than my full specs I'm runnig a 701 62t bigbore R&D pipe dual 48 blackjacks blowsion modified head best setup I've ever had