GL63 launches much better than S63 - why?
 

Relative newbie to the MB & AMG world here. I have a '14 S63 and a '15 GL63. Put each one in sport mode, and from a dead stop the GL immediately pulls hard off the line. The S on the other hand rolls out lazily for a few moments until the turbos spool up and only then starts pulling hard. Normal? Would a tune improve the S off the line?