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June 2015:

We've been so busy building wiring harnesses for you that we haven't made a website update! Here at Tweak'd Performance we've improved and streamlined our production process to offer unmatched customizability for your wiring harness needs. Are you running a stock ECU? AEM? ECUMaster? Haltech? ProEFI? Infinity? GM coils? ID2000, ID1000, Bosch, Denso injectors, flex fuel, no problem. We carry in stock every connector for every single EMS, injector, and coil option so when you order a harness from us we can have it put together and sent your way as quickly as the next day for extremely urgent jobs! Equally important as speed and customizability is the fact that all of our harnesses are made here in the USA, while many companies send their production to be done in totalitarian countries with unethical labor practices. Think about where you're sending your money, check the reviews and feedback on the forums, and then give us a call!

Tweak'd Performance – Fully customizable wiring harnesses for GM LS1, LS2, Toyota 1JZ, 2JZ, 1UZ engines, every variation of VVTi and non-VVTi, dual ECU, CAN BUS solutions, and new products are on the way!

Have a harness idea that you want Tweak'd to build? Give us a call, wholesale pricing is available.

March 2013:
NEW from Tweak'd Performance:
Plug and play wiring harnesses for ProEFI and Haltech Engine Management Systems!

Are you running an aftermarket EMS with your new engine swap, such as a Sport 2000 from Haltech or Pro128 from ProEFI? No problem! Forget about dangling connectors from unneeded sensors or cutting and splicing different injector plugs into your harness. No need for one of those bulky patch harnesses either! Get a BRAND NEW harness from Tweak'd Performance that's slim, tidy, tucked away, and doesn't have any unnecessary connectors or wire, and goes STRAIGHT to your new EMS. We have all new ECU connectors and terminals in stock so just let us know which EMS you're using for your project and we'll get you taken care of! Give us a call today at 1-800-533-6775 or email us at!

March 2013:
Expanded Line for Plug and Play Conversions:

2JZ and 1JZ swaps into BMW, Nissan 300ZX, 350Z, Hyundai Genesis, and Scion FR-S!!!

For years Tweak'd Performance has offered Self-Contained 2JZ and 1JZ engine harnesses for more unique cross-platform engine swaps, but this year we're taking it to another level by offering 100% PLUG & PLAY harnesses for some non-Toyota vehicles, including BMW cars, the Nissan 300zx and 350Z, the Hyundai Genesis, and the all-new Scion FR-S! For a quote on a plug and play solution to your engine swap, send us an email or give us a call at 1-800-533-6775!

March 2013:
New Product From Tweak'd Performance:

LS1 Wiring Conversions for Supra, SC300, etc!

Over the past few years, the LS1 engine swap has started becoming more and more popular, and we've gotten enough calls and requests for this wiring conversion that we've decided to add it to our standard services. Plug and play wiring conversions are now available for all LS engines into any Toyota chassis!

Feb 2013:
Did you see us in the latest issue of Super Street Magazine?

Thank you to our customer Ranz Performance and Super Street Magazine for mentioning our work in the March 2013 issue. Check it out!

Jan 2013: Project Jumpstart begins! Special discounts on all wiring harnesses, conversions, and parts from now until Feburary 8th! Contact us today to take advantage of this special deal before we change to 2013 pricing!

Jan 2013:  New Product from Tweak'd Performance: 2JZ-GTE VVTi Engine Harnesses! Also available with braided sleeving and MIL-SPEC firewall connector!

Harness available in our online store

Jan 2013: Also new this month: NEW 7MGTE Engine Harnesses! Replace that crusty old wiring harness on your MK3 Supra Turbo with one of these new, updated replacement harnesses!

Harness available in our online store

Dec 2012: Here at Tweak'd Performance we're happy to release our new MIL-SPEC wiring harnesses. Eliminate your old rubber firewall grommet with these extreme-duty MIL-SPEC bulkhead connectors for the ultimate clean look and the very best harness protection available. Pictures shown alongside our EXTREME DUTY heatshrink looming:

Contact us today at or call 800-533-6775 to see how a MIL-SPEC harness can be used for your application!

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