It's your choice, but we never had any luck with AVGAS instead of race gas. We had a lot of detonation......it just didn't work. In addition, some AVGAS has some alcohol in it which can deteriorate fuel lines, etc.

I'm not saying not to, but be careful. You get what you pay for. I'm not a gasoline expert, but there are some differences between automotive and aircraft demands....there is more to it than just octane.