i have a friend here that works for barry grant, he is getting me a speed demon for $150, i have a bored 352 with a fairly large cam, a dual plane edelbrock intake and a full msd ignition system. i was looking a the 575cfm and the 650cfm, i think that the 650 may be a little big for my motor and the 575 might be a little on the small side, i have a 600 holley on it now which works fine but im 18 and basically for $150 i have to have a carb that says demon on the front of it, that how us teenagers are haha. anyway i was wondering if you would go with the 650 or the 575 and also i was looking and they offer both of them in mechanical and vacuum secondaries, will mechanical ones get a lot worse gas milege or do they do alright. i am only making 10mpg as of no so i dont want it to get any worse, i have only owned vacuum operated secondaries so i dont really have any experience with mechanical ones.
thank you
Tyler