I am running Hookers 2462 1hkr Competition Series headers on my 1997 Vortec 350 and these headers are designed for the 88-95 TBI trucks. I just deleted teh EGR via teh PCM and disabled teh raer O2 sensors and installed front O2 sensor bungs in the headpieps just after the header collectors.
Exhaust, headers, mild 97 cotane fastvchip pCm dropped my 1/4 mile time by 3/4's of a second.
peace
Hog