Hey Ace....I purchased an 05 GP Comp G in Sept 07 and did a "GM Vintage" search (GM does charge for this). You can do this for any GM vehicle and get the options installed, production info etc.
Now these figures I'll give you are Can figures. You can probably multiply by 10 to get US based figures as an approx.
In Canada, 421 GTP's were produced for sale. 209 of these were the Comp G package. 103 in colour 12 (silver).
Hope this helps. If you want the GM Vintage number let me know.
Cheers