I have an 800 so I don't really know whats different on the 500. On the 800 you can clock the secondary and get more acceleration if the 500 is the same its not too hard and there are some guides to doing it. Exhaust I wouldn't bother with they are expensive and don't do much for power and just make them annoyingly loud. There are chips and stuff they may make slight difference (not worth it IMO). Your best power gain feel will be with clutching by far I would concentrate there. As far as the A-arms If the main frames are the same (I assume they are) they will bolt on, if you have the same width stance as an 800 then the A-arms are likely the same so 800 parts would work. I would just look up parts for the 500 and 800 and compare part numbers for the arms. This is ALL speculation. I don't have a 500 and have never even seen one in person.