Reading back struggling to see the debate, except I think some are talking about power and the feeling of quick, which has little to do with each other. Currently own a Z4 35is and a Mk3 Focus RS. The Z4 is stock, just not felt the need for more, but the RS runs a map giving around 400. It also produces more torque and has better traction and is quicker on paper. BUT, the Z4 "feels" quicker of the two, reason is simple and perhaps is what some are missing above. Torque and where the peak is and how flat the curve is. To be technical, it's the area under the curve that is important. The Z4 hits peak torque and holds it from about 1800 rpm, then is flat, matched to a 7 speed box not a 6 as in the RS, a lower final drive ratio it pulls early and hard and doesn't let off. The RS torque is more progressive and builds, so feels less urgent, even if it's actually the quicker car.
My Z has done 76K miles, I have most of the history, seems to have been well behaved, it is a glorious engine, in sport mode and box in sport it is relentless and savage, in comfort it purrs and burbles like a little puppy. Truth is the RS would be in the next county given a few twisty bends before the Z could get it's nose pointing in the right direction, but then very little will keep with an RS on the twisties, less so a mod'd one. ( I am lucky to to own two great cars, love them both).