The 21 would light up the rears, in 2wd. I didn’t beat on it too much though. It just seemed a little held back, esp based on how hard it pulled once moving. My 18 would break all 4 or 3 loose for a second or so. The 18 will obliterate the rears if I’d let it, the 21 not as much. It’s brand new though, it should loosen up. And once moving, both truck have some sweet spots at different speeds for accelerating, but the 21 definitely had more. The 21 is a little funnier to drive, even though it is ugly.