Not every Vortec TBI engine needs the 18 PSI fuel pressure regulator spring. Try a stock fuel pressure regulator?

Most Vortec TBI engines see a measurable improvement with a Vortec Timing Table vs. a TBI Timing Table, see link: http://www.gearhead-efi.com/Fuel-Inj...-Throttle-ONLY!

Wide Band O2 Tuning is a good plan, see link: http://www.gearhead-efi.com/Fuel-Inj...g)-Spreadsheet

dave w