Just to clear this up, hes looking for top speed, not "top end"
top end is when the power is mostly in the upper rpms or revs ot really fast and high.
the only mods that will gain speed is gearing, but in doing so, your gonna loose power noicably. i run 15-38 on 18s and in a speed trap top of 5th is 55 miles a hour if that helps thats roughly the same as 14-40 on 22s or 14-38 on 20s