RENNtech Intermediate ECU Upgrade | R231 | SL 63 AMG | 638 HP / 695 LB-FT | M157 | 5.5L V8 BiTurbo | MY2012-14 mercedes-benz-s-class--221---2007-2013--s-63-amg-esr7422703 ECU+ Upgrade | Up to

ECU+ Upgrade | Up to 659HP / 614LB-FT | Gains: +84HP & +93LB-FT

Intermediate ECU Upgrade | Up to 638HP / 695LB-FT | Gains: +33HP & +49LB-FT

Its unique design complements the refined trunk lines yet offers a more aggressive

The two-piece carbon fiber diffuser is finished in a high gloss UV protectant clear coat

RENNtech Intermediate ECU Upgrade | R231 | SL 63 AMG | 638 HP / 695 LB-FT | M157 | 5.5L V8 BiTurbo | MY2012-14 mercedes-benz-s-class--221---2007-2013--s-63-amg-esr7422703 ECU+ Upgrade | Up toIntermediate ECU Upgrade Up to 638HP 695TQ Gains: +75HP +101TQ RENNtech HHT (hand held tuner) allows you the unlimited ability to switch between tuned and stock ECU programming and requires no ECU removal! Our proprietary tuning module stores both the RENNtech tuned file and your vehicles stock file. The module plugs directly into the OBD2 port and delivers the file you choose directly to the ECU. Programming takes only a few minutes and the vehicle