If you are looking for quality production, mini-x is not the best choice. I would suggest ABC DTM X4 instead. Regarding CPR unit, I believe you can search on this forum for it. I have seen someone posting his mini-x with cpr unit all together. If price is critical, you might want to get Kawada M24-Mid instead. I got mini-z, mini-x, micro rs4, indoor racer, m24-mid as well as dtm x4. The Kawada m24-mid is the most flexible one in the current market with afforable price and quality. You don't have to buy tons fo hop-ups. I would suggest to get ball bearing and 180 motor though.