What exhaust will be the best for my unrestricted kymco agility 50 4t. Will need one soon. Mybe the original exhaust the best. Any help welcome. At the moment I use a 2005 agility 50 4t race variator. Up jetting 84. 70 kph on flat roads fast down hills. My exhaust is rusty around the mounts. Done 25,000 miles.