tpi wiring harness | eBay Find great deals on eBay for tpi wiring harness. Shop with confidence. Skip to main content. eBay Logo: 1987 FIREBIRD TRANS AM GTA 5.7 TPI ENGINE WIRING HARNESS ECM COMPUTER WIRES 350. Pre-Owned. $297. Buy It Now. Free Shipping. 1991 92 GM CAMARO SPEED DENSITY TPI 5.0 5.7 COMPLETE ENGINE WIRING HARNESS OEM. Pre-Owned. Larrys Electric - Universal Tuned Port Injection harness Tuned Port Injection stand alone EFI wiring harness . This harness takes care of the headaches involved with installing Tuned port injection on most all SBC engines or swapping a TPI engine into your vehicle, and makes for a much easier installation. Our harnesses are all made with top of the line copper strand wire.