[rphubbard]

Tongue Pirate,
The reason for the switch to 91 is for only one reason and that is the supply pipeline only wants to handle as few different levels of gas as possible so everyone agreed to 91 octane. It has nothing to do with emissions.
As far as octane booster, I worked for Roush for a couple of years and just left the company due to downsizing, I have stayed with octane booster because of things I have seen at work. But you have to be careful on what brands you do buy. I like the NOS brand and some others. I would also recommend mixing turbo blue with your fuel. But I am just leary of paint thinner but it doesn't seem to hurt. I found one bottle does the trick for me in my 65 gallon tank so a little bit goes a long ways for me.