Hi Kev,
Your advice has been much appreciated since I bought an 05 xtx a few months back, I did the "Kev" mod & altered the CO value & tried changing the TPS value but my bike still banged & popped on a closed throttle from any rpm & the surging improved slightly but remained.
To learn more I installed a O2 sensor port in the header and fitted my A/F ratio meter and went for some rides.
I worked through each mod in sequence and monitored the result.
Each mod produced a slight change in exhaust O2 readings around idle and slightly above but none of the changes affected the indicated fuel mixture at cruise or full throttle !
I tried going both ways on the CO value to the point of stalling on a low setting but still no change on rpm above fast idle.
This data corespondes to the "feel" of the bike as I could only detect changes around idle performance and no change in general engine behaviour.
My bike has hi flow air filter, Yamaha racing pipes and I cut the "crimped" end off each header (4mm) as the flowbench showed significant restriction from that, it was also causing a lot of flow through the ballance pipe which as the headers are paired obviously could not go anywhere.
As many other riders have found improvements from the mods across the entire rev range I am curious why my bike hasn't responded the same but the test rig I used has proven accurate on other bikes / cars.
I'll keep at it until I find some explanation.
Nick, Auck, New Zealand