Tuning firms will do whatever they can to eek out every last bit of performance possible - it’s their nature. That holds true whether its the definition of ‘econo-box’ like the Smart ForTwo or a production powerhouse in its own right, like the Mercedes CL65 AMG. RENNtech has turned its attention to the latter, and the result is - put simply - insane.

The stock CL65 AMG is no push-over, generating 612hp from its twin-turbo V12. But RENNtech decided that just wasn’t enough, and through use of special ECU software has upped output to a massive 695hp and 890lb-ft of torque. Looks like the horsepower war didn’t end - it just got outsourced.

The remainder of the new ‘PKG3′ tuning fitment includes a larger intercooler pump and an additional heat exchanger to keep the V12 cool, and twin carbon fiber airboxes to improve airflow. The combination reduces intake temperatures by 20 degrees, making more consistent power and improving the ECU tuning’s effectiveness by allowing boost to be increased with greater safety. A set of stainless steel sport mufflers change the exhaust note to keep the luxury feel but add a more aggressive tone.

Pricing for the PKG365 (stage 3, 65-series) upgrade package starts at $18,990 plus installation fees. It is available for the S65, CL65 and SL65 AMGs.