Anthony and I spent a good bit of time on the dyno yesterday finalizing the Stg 1 tunes for our F10 M5. Interesting to note that the aftermarket exhaust didn’t improve power on our 2015 M5 with Competition Package. But it did save ~50lbs and improved sound which is always a nice thing. Keep in mind that this car is still running OEM downpipes/catalysts. I like my cars (and air) clean so going cat-less was not an option. All testing done on 91oct fuel.
The fun really started when we remapped the ECU. We developed two version of OFT Stage 1: One with Full Torque and one with Flat Torque. The Full Torque version is just that, a tune that provides generous torque in the low end and midrange. We still limited peak torque to 585lb-ft which is a reflection on our restraint since the car is capable of producing much more at the expense of repeatability and excessive engine stress.
But it’s the Flat Torque version of the tune which is novel. We purposely limited torque to stock-like torque levels. But keep it flat as possible throughout the rev range. This was still worth a nearly 100whp gain over stock. The nice thing about this Flat Torque tune is that it feels really rev happy, predictable, and easy to drive on the road. Almost as if it had a naturally aspirated engine. It begs to be revved out and feels repeatable pull after pull. Compared the more traditional Full Torque tune, this tune feels like you can beat on it all day and it will never miss a beat. Engine sounds and feels unstressed which always encourages hooliganism