I put a ohlins shock from a cbr600 f3 on my mc-18 it seams to work really well. It's about 1 inch longer than the stock shock makes up the difference if you switch to a 17 inch rear wheel. It took a while to find on e-bay. You could also look for a Penske, or Fox shock for the CBR F3. You will need to have the bushings machined a little.
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