I tried the cheap octane booster with less than 1/4 showing on the fuel gauge, so no more than 5 gallons left in the tank. I was still able to make it knock. I can't say for sure if it helped at all but it didn't totally prevent knock.
Before I did that, though, I found out that it won't knock when it's cold (or even warm but not hot). I had to drive it for a half hour, including 15 minutes at 65mph on the highway, before I could make it knock. I've read that the Buick 4.1 is tough to keep cool. I suspect that mine runs pretty hot. Then there's that hot underhood air that it uses. I wonder if I should add a lower-temp thermostat and fan clutch to my list.
So, my list of things to try...
- CAI
- carbon removal (Seafoam? Italian tune-up? Water?)
- port vacuum (probably fail but it's way easy and free)
- EGR
- retard timing
- octane
- cooling (fan clutch and thermostat)
A rubber pipe from the S10 is a nice fit for part of the CAI if I do it.
I could probably sneak it right through that space to the right of the radiator and have it breathe directly behind the grille.