after a bit of a fiddle ( and a phone call to "Steve - UK", thanks Steve ) I fitted the Sprint Booster without removing anything. Did the throttle reset and went for a spin. I think it turns it into the car it should have been, a much sportier response and gets rid of that Mercedes "make it all soft for luxury saloons drivers" approach. It also seems to have changed the exhaust note , sounds like someone sneaked in a V8 when I wasn't looking. Possibly a bit of a handful if you aren't prepared for it, or into that style of driving. Ideally you could switch it on and off with a button. I don't think Anne will drive the car now !!

Definitely a good purchase, loads of fun, came back with a big smile on my face