if all you after is top speed runs, then its going to take one hell of a .21 to match that Picco 28... ... That big 28 does make a real 2 HP, those .21's make 1.5-1.7 HP at best, with nowhere near the tourque.....The big 28 will be able to push very high gearing and not break a sweat...... Top Speed is all about gearing and HP, and the Picco 28 has very big HP