TPI Wire Harness - speedscenewiring TPI Wire Harness. 1991 Y-Body design fits the Corvette engine and can also be made to operate the F-Body engines. The computers from this era have someting called VATS (Vehicle Anti-Theft System) this is removed on all Speed Scene Wiring harness through a computer process. The layout is uniform on all Stand Alone harnesses built from scratch. GM TPI Wiring-Ron Francis Wiring TP-50 Chevy TPI Telorvek Fuel Injection Wiring Our harness upgrades the 1985 through 1989 engines by running them on the 1990-92 Camaro or Firebird computer. Using the 1985-89 engine, the computer, prom, and knock sensor will have to be changed to 1990-92 components.