i know its not a GT but this is my input on the stock vs DP kit vs PCIII USB. as you can see in the dyno graphs it helps lot. stock is alittle to lean, the DP kit is alittle to rich. the PCIII works out grate.
http://www.ducati.ms/forums/showthread.php?t=22430
http://www.ducati.ms/forums/showthread.php?t=22430