Actually thats the 4th Octane booster I've tried. I've been keeping track of the effects it has on my MPG (Z's have a built in calculator on the MFD) and responsiveness.

So far the STP seems to be the best stuff for the money. This is in preparation for mods planned for later this summer. I wanted to have a feel for how the car should feel running this stuff while in a stock configuration so there wouldn't be any surprises down the road.

I also didn't let any pre-concieved notions get in the way of my testing. The NoS stuff does work great, its just expensive as hell (2-3x as much) compared to the other stuff out there.