What with the HP4 being the flagship of BMW’s sportsbike range this one came in for the full monty ECU remap. The owner already had a full exhaust system fitted and felt that it wasn’t running as good as it should be – we checked it on the Dyno and sure enough, it was running lean.

This, as we’ve said many times is always the problem with open cans/exhausts if the intake side of the engine isn’t also addressed. We added the K&N filter and sweetened up the fuelling by giving it what it needed – more fuel. Which sorted the throttle response out a treat.

A lean running HP4 sorted with an ECU remap...

A lean running HP4 sorted with an ECU remap…