Increase the power and drivability of your 675LT by optimizing the ECU. We've had ample time with 657LT's on our in-house Dynojet to unlock extra power on both stock vehicles and optimize performance with our performance downpipes. Once we receive your ECU, our tuner bench flashes it with the upgraded ECU map and we return it to you for easy reinstallation; no modifications to the vehicle are necessary. Trust Fabspeed with your baby - we've been improving McLarens since day 1 of the MP4-12C and we're dedicated enthusiasts with our own MP4-12C development car! Our top notch facility is outfitted to produce the finest exhausts and thoroughly test the results - all while extracting maximum performance with a tune to match. We have optimized files for vehicles running our Sport Catalytic Converters and Catbypass Pipes as well to ensure you are making the most possible power, reliability and realistically: POWER GAINS - Stock Hardware Stock = 582 whp / 490 ft-lbs Tuned = 629 whp / 516 ft-lbs Maximum gains of over 65 whp and 43 ft-lbs of torque at 8000 RPM Peak power gains of 46 whp and 26 ft-lbs of torque POWER GAINS - With Fabspeed Sport Catalytic Converters With Sport Cats = 600 whp / 510 ft-lbs Sport Cats + Tune = 635 whp / 526 ft-lbs Maximum gains of over 56 whp and 45 ft-lbs of torque at 6450 RPM "Who is your tuner?" Steve has been tuning cars for many years. Steve has written software being used by many other companies. He has been the first to crack ECU's before anyone else. Thousands of vehicles are running around this world with his tunes, everything from 500 WHP Hondas to twin turbo Huracans, and your car is next. Put your faith in our tuning genius. "Will this affect my warranty or vehicle reliability?" We cannot say it will, nor that it won't. It is ultimately up to your dealership to make that call. We do extensive testing to ensure our products are reliable and engine safety is a consideration, especially with our tune. We don't craft our tunes purely for the highest numbers for bragging rights, rather the most excitement you can get without ever having to worry about a tow home from the race track. "Sounds good, how much do I owe you?" $3,495.00 is MSRP, but shoot me a PM and I'll take care of you. "How do I get to my ECU?" Easy. Remove the passenger side rear wheel well to expose the ECU, disconnect the harness, and pull it from the vehicle. [ame]http://www.youtube.com/watch?v=wR9fke5UVUA[/ame] Shipping costs for sending an ECU to Fabspeed is the responsibility of the purchaser. The ECU will be tuned within 24-48 hours of receiving it and we will then ship back the ECU overnight to US customers and expedited worldwide to our out of country friends. If you go to dealership, we can flash it back to stock we always keep the factory file. Reflashing - $250 Scenario A: We can reflash the Fabspeed ECU Tune back onto the ECU if it is overwritten by the dealership - Return shipping is covered by us. Scenario B: We will reflash the ECU back to the OEM configuration and return it to you, shipping covered by us. We will then reflash the Fabspeed ECU Tune back onto the ECU All shipping would be covered by you. See all information here on our website. If you have any questions - we're here to answer them!