I would like to see some other members run their GXPs at the track to get some additional data. I would say anyone taking their GXP to the track should run premium fuel only for at least a few weeks before going to the track. I think the GXP needs premium fuel to run to its potential. The SSEi guys know to run premium, but I'm not sure if the GXP guys do.
Something else I should mention. I did a search of this site, and there is a lot of talk about the TM and TC cutting power even when TC is switched off. My car does not seem to be limited in that area at all. On asphalt, if I stomp it off the line, it will spin the tires almost all the way through first every time. On concrete it varies, in warm weather it might just break the tires loose for a second, or it might spin 1/2 way through first or a little more. It won't do this until it has been warmed up for at least 5 minutes though.
On wet pavement, with the TC on, I can feel it limiting power at part throttle when the tires break loose. However if I floor it on wet pavement, it will spin the fronts real good, get the tach up to 4 or 5 k while spinning.
I guess what I'm getting at is that my car seems to be pretty liberal in the area of TC and TM. Makes me wonder if later 2005 PCMs had adjustments in this area.
Anyway, I plan on building a CAI and taking it back to the track this fall. I expect to squeeze at least a 14.50 out of it, but we will see.
At some point I do want to install the same ZEX 75 hp kit that you are running.