[Tinsta]

Litchfield use Ecutek which not only gives you a remap, but the ability to have different maps easily switchable via the steering wheel controls.. so you can one map for 95ron, or another one for cold/wet days where you need the torque/power turned down (or even a valet mode, if the car goes for a service). They've done numerous S55 remaps and have a good database of maps now.

Used them for the last 10yrs on other cars without issue, will get mine done in a few months once I've done the crankhub fix (as a precaution).