Dad VS Son ????help

My 9 yr old son, some of my friends and me, where at my friends MX track. Very nice, fun, and difficult track with alot of jumps. My son was doing laps on my 450r, so I hopped on my friends Suzuki 250r, which is almost as fast as the 450r, but dont quite handle as well, and decided to follow him to see how he did. I found that I couldnt even stay up with him. I couldnt believe it. I still dont beileve the way that kid can ride that thing...I learned a couple of things following him.

What do you do when your 100 pound 9 year old has exceeded the limits of his built up 200 blaster, and needs something way faster and better. But everyone looks at you like your stupid if hes on anything bigger then a 100. My kid started on a 100cc 2 stroke, and that lasted like 5 min...I want to buy him a bigger faster 4 wheeler then his blaster, but he is too young. what do I do?