dosnt the size of the turbines play a part in when the turbo spools up 
small turbo = spool up fast = more bottom end, big turbo = spools up slow = more top end, a free flowing airfilter and exhast helps the turbo spool faster as well
right,
but for rock crawling a turbo is about as useful as tits on a boar hog,
but you would have the impact power on the highway to and from the trail, but you better use a "R" series tranny
