What's it going to take to run high octane gas in my L67, O2 sims'?
I live in Decatur, Mi, home of Evan Knoll, Torco Racing Fuels, and Knoll Gas, which is .2 miles from my house. They have 110 and 112 octane gas at the pumps there, as this is Evan Knolls store.
Not saying I want to run it everyday, but on those special occasions, well...

 

You can just dump it in. It won't make a differance. If you want to get performance bonuses from it you would increase timing and boost with a smaller pulley.

Your big concern is to find out if it has lead additives as that will ruin your front O2 sensor quickly.

 

If I replace the O2 sensors with sim's, and get this HP tuner to adjust things, then I should be OK? What about valve guides or anything else other than the O2 sensors?

 

The O2 simulators don't work for the 04 Monte's as that is when GM changed the way they work. They used to only measure O2, but now they also check heat and the O2 sims don't look at this.

Don't need to worry about the valve guides.