I have a 95 Sierra Z71 with an Edelbrock Performer TBI intake, Edelbrock Performer stubby headers, a heavy duty rv cam, Helix throttlebody spacer, MSD 6A ignition box, Holley 670 throttlebody, and dual 2 3/4 inch exhaust with Cherry bomb mufflers ending in front of the rear axle. Any one of these things or combinations of them will increase your horsepower, but the maximum you will pull from the bbl intake is around 300 horse.
I hope this gives you some ideas to look into.
