Then what does moving the shifter to the left do? Both the button and the left-shifter display DS. I thought the "S" in DS stood for "Sport" mode.

 

It changes the shift points. That's all.

 

http://blogs.insideline.com/roadtest...overboost.html

https://www.northamericanmotoring.com/forums/drivetrain-cooper-s/126599-how-does-overboost-work.html

sounds to me like the Sport button adds temporary boost?

 

That article is talking about what happens when you "floor it" (actually, get beyond a certain point in the accelerator pedal travel). As far as I can tell this seems to be independent of the Sport button and/or the shifter.

 

Here's how I have always understood it all to work (for an auto trans):
selector in D = normal shift speeds, normal steering effort, normal throttle sensitivity, no overboost available
selector in DS = quicker shift speeds and high rpm shift points, no overboost available
selector in DS + Sport button on = quicker shift speeds and high rpm shift points, heavier steering effort, high throttle sensitivity, overboost available (2007-2010 Overboost: 192 lbs ft (260Nm) from 1700-4500)
selector in M + Sport button on = quicker shift speeds, manual shifting expected with paddles or selector +/- gate, heavier steering effort, high throttle sensitivity, overboost available (2007-2010 Overboost: 192 lbs ft (260Nm) from 1700-4500)

How does that sound? my overboost specs came right out of a MINI spec document I have here at work. If overboost does not add more boost as many above have stated, then how does it gain measurable torque?

 

I have a noticeable "click" (with slightly increased resistance) in my gas pedal once I push it beyond maybe 80-90% travel - almost like I'm "pushing a button" with my foot. Anyone else have this? I assumed that was the overboost "button" (for lack of a better term).

 

Assuming you have an automatic, what you're feeling is the "kickdown" switch which forces a downshift (or two) for maximum acceleration.

 

Sport button???