RENNtech | ECU HHT-Hand Held Tuner | R230 | SL 600 | 625 HP / 745 LB-FT | 5.5L V12 BiTurbo | M275 | MY2004-2006RENNtech ECU HHT (HandHeldTuner) for the 230 SL 600. Up to 625HP and 745 LB FT LB FT. Gains: +133HP & +155LB FT. 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.