I'm 68 now and snowmobiling is my passion. I keep in shape in the summer by ridding my pedal road bike. The older I get the faster I was. I use to enjoy racing young guys and usually beating 90% of them up until I hit 66. Now it seems like my bike isn't as fast as it use to be. That being said, I still ride my 1100 turbo 4 stroke 215 HP cat as good as anybody. I love it when I pull up to a group of guys on 2 strokes looking to go into some bad *** country where I came from and they ask me it the weight of the 4 stroke is a problem. I tell them that I'm 67 and that the weight isn't a problem at all when the ski's are 2 feet in the air she feels really light but you should probably stay with your 2 strokes cause 215 HP is a huge difference when compared to a 800 at 10,000 feet. Going up the mountain is still and hoot and my biggest problem now is going down, also seems like going down is really scary the older I get and I don't jump off snow cornices any more.