Good news for me... maybe with a fresh dose of lower octane, i will see 80mph.

One thing about avgas you should know,,,,,,it has bromide in it which scavenges carbon/lead deposits from the pistons and combustion chambers. Bromide is also highly corrosive after the combustion process, which is why aircraft have stainless steel exhaust components. I'd think real hard before using it in an engine with aluminum or soft iron exhaust components.

AV gas is a little hard to get now. Our local airport has you sign a waiver that is required by the FAA that states that the gas will only be used in aircraft, period.
It is a little expensive at about 3.25 per gallon, but it has a great shelf life. Personally, using the Sunoco race gas makes more sense, since it is readily available around our area for a little under $3 per gallon. There are a lot of race teams here
I do like using AV gas for winter storage though

You mention bad for the exhaust how about engine internals. If its bad for Aluminum or soft iron, its got to reck havok on pistons over time???!!! This is the first I've heard of this, now you got me wondering!