which maf, 77mm or 83mm?? help!

[acidangel316]

whats up. i have a almost stock 94 cobra and my maf crapped out on me. i had a 73mm c&l on it. i was wondering what the difference is in bigger mafs? will it hurt my gas mileage or my torque? and, i want to run a afm power pipe and for my car they only make them for pro-m 77-83. should i just go with the 80 for more horses? what's good and bad about the different sizes?

thanks, josh

p.s. my car has 1/2 an exhaust, pulleys, 60mm tb but soon to be a 70mm, b-cam, soon to get heads back from machine shop...