Scotty I was going to say exactly what mildman did.
As a 16 yr old I terrorized the streets of Las Vegas with a 9 HP Yamaha DT100 , nothing like standing in your front yard watering your lawn and seeing a 90lb kid come flying round the corner at 35 mph draggin the foot peg in a lovely feet up slide........this behaviour was quickly followed by hanging way off and draggin my knee.....all on trials universal tires , so needless to say the bike slid around a whole lot.
Flash forward 27 years and one of my racing buddies has the same model as a pit bike, when I saw it a started laughing. He wanted to know what was so funny. I told him that I used to race through the old Railroad yard on that.....he thought I was nuts and frankly looking at the bike now I can't believe I rode one on that manner.
So if your one of those 16 year olds who is pretty mellow then an A14 or 15 convert will be great if your like me and mildman then leave it stock.....that way if you do crash you'll be going slower.
Tom