i have an itr tranny on my turbo gsr, and i love it, i like it better then my previous GSR tranny...

that is too general to say "turbo car's do better with a certain tranny" for most application's a gsr tranny will be just fine, but it also depends on your turbo if you have a big mother fawking turbo that dosen't open up tilll about 6 grand then yes longer gears would be great choice, but if you have a smaller turbo that will open up at about 3700 rpms an ITR tranny will be just fine... so its all relative to the set up