You didn't bring it up. But I would suggest a new air intake. Pretty cheap if do it right. Can buy uni off amazon or ebay. And I went to an exhaust shop and just asked for scrap piece of pipe for the intake pipe. Then buy a rubber attachment from home depo. Or they got some on line around 10 or 15.
Better then buying the kits for around 100.
Suggest exhaust also. Or modify the one on it.
I get your not looking to beef up, for kids. But will be much easier on engine. And don't kid yourself. You will be driving it also.
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Look into some lighter wieghts for the ctv. I like 10g for my kids. Takes a while to get to top speed. Plus, keeps power in lower band if you need it. 10 might be to light. 11 or 12 might be better, depending on what you want.
Just stuff I can think of off top of head. Ohhhh. Get some decent seat belts. That's a MUST, with kids in that model of yerfdog. Trust me.