Throttle Body Shop TBS 10321 GM TBI 18 Psi "RED" Fuel Pressure Spring TBI 18psi "RED" fuel regulator replacement spring Fits: 1986-95 2.8L 4.3L 5.0L 5.7L 7.4L TBI motors For modified motors it bumps stock TBI fuel pressure from 11-12psi to 18-19psi - fits OEM regulator can This spring will require a fuel pump upgrade for the increased pressure - see our store for this 2nd photo shows typical TBI injector assembly these fit Silverado Sierra Suburban Yukon Blazer Camaro Firebird Caprice S10 Jimmy