I have a 2.18. i bought it new for 100 dollars. The engine didnt seem as strong as i though after a gallon thru it. I replaced the ring with a Bowman ring, we looked it over. we raised the exhaust a tad and widened it, opened up the carb and did some minor port match. it now turn the XOAR 20x10 at 7,500 on 5% still not as strong as i though it should be but it is 200 rpm stronger than my Moki 2.10 on the same prop and muffler. Also any muffler/header that fits the Moki will fit the MDS 2.18 there are two Moki 2.10 on RCU for 150-175 dollars NIB.