all depends on were you plan to run....I will say that the 2 spd is not much faster then the 3 diff but yeah it is faster....if you plan to run on a track the 2spd is useless in my opinion...I prefer the 3 diff due to the fact that were I run is a small course with jumps and I would never hit 2nd...if you run on the street mostly u may prefer 2spd...I do think a 3 diff will get outta the hole faster then 2spd...I also beleive that a 3 diff is easier to maintain