the ace is a fenomenal servo, the tower pro not so much, its gonna give up soon, when it does get the 1015 then and throw it up front. no looking back after that. i would not use the "cheeper" servo in throttle cause when it goes bad your car may be gone into something or someone. not that the ace wouldn't fail but i've had mine about a year now, no issues. the 1313 is a really good steering servo, the 1015 is only slightly better all around.