I can't see that it has any feelable turbo lag seeing as its a TWIN SCROLL turbo, its design as been to prevent turbo lag due to overboost on acceleration. I will try to find the TOP GEAR write up on the COOPER S and WORKS that gives precise reasons for the car having no noticable lag at-all unless you are part bionic dyno.
I think because you know that turbo's commonly have lag you are convincing yourself that there is some when truthfully theres not. And what i find funny is that whether it has lag or not it is ultimately quicker that the 1st Gen cooper s works so why would it matter??
Don't get me wrong i prefere alot of things about the SUPERCHARGED Mini, i stick up for them being a whole lot more fun than the turbo in alot of ways. ie supercharger winding, constant feeling of power. But in general the R56 is a completely refined car so even for that reason its a good step to take.
Joe