im looking for motor mods anything from mild to extreme and companies that sell parts for them. also any tips or tricks on the efis.

 

Not a whole lot you can do to an efi, carb is a different story. For efi you can put a more agressive cam, head work, bigger injectors, headers (not a whole lot better than stock manifolds), true dual exhaust, ignition upgrades.
Manufacturers
Clifford, Offenhauser, Isky Cams, Headman Hedders, MSD, Crane, Ignitor