I read my Owners Manual for my '08 R55 Clubman concerning the the sport mode and it said that it tightened up the steering and the throttle response. It does both of those things, but it doesn't mention any suspension changes.
My question is; if it has no effect on springs or shocks, why do they specify a different front shock for sport equipped models?

 

You also get a thicker anti roll bar, with sports packs
I'm sure the sports button has no effect there

 

I owned a 2007 R56 and now a 2013 R58. They both responded equally when in sport mode: stiffer steering, quicker throttle response, and exhaust burble. Perhaps those that say they don’t notice a difference in engine throttle response or exhaust sound, are you running less than premium fuel, or do you have check engine light? These cars are smart. If the engine is cold, isn’t running perfect or you have low grade fuel, it protects itself by reducing performance.

 

Pay attention to the AC/defrost. If your HVAC system is on at all it will have a tendency to have much less of, if it all the pops and bangs. Heck even electric load will minimally ( and i mean minimal, but still there) have an effect. The alternator and battery. (Week or low battery, then the alt will be dragin harder on the serpentine. Basically anything that is going to slow the Centrifugal force of the rotating mass that is not drivetrain) make the back end of the motor control the front end..... i know i sounds like an idoit but its just my observation.