Dinan D900-S55-S1-W-HE is Dinan+ performance engine software for 2015-2020 BMW M2 Competition, M3, and M4 F80/F82/F83/F87 models. The calibration is designed specifically to work with the Dinan D780-0001A S55 heat exchanger and adds power, improved drivability, and removal of the factory top-speed governor while retaining BMW engine safeguards. Dinan lists maximum gains up to 90 HP and 97 lb-ft on the M2 Competition and up to 75 HP and 88 lb-ft on the M3/M4. It requires the Dinan heat exchanger for advertised gains and warranty coverage and is intended for racing-use-only vehicles under Dinan's current emissions listing.