No problem. Just took a couple clicks to move it here. And I remember your enthusiasm. I had it almost 3 years ago. Googled and Web Ferret'ed till the sun came up night after night searching. One plus is I did learn alot about Northstar engines. Nitrous does wake the engine up to the extent you actually accomplish something more than the little tweaks and improvements shown by alot of that other stuff. It isnt that they dont work, but they are more designed for the 1/4 miler trying to squeak out a couple tenths of a second. Just some ball park figures here. $150 for a TB rebore, $300 for a maf, $100 for a cold air intake, and get maybe 8-12% increase in power. I wasnt about to bite into that.
If you consider Nitrous, those cheaper "dry" kits you referenced will burn your engine up and what gave nitrous a bad name to begin with. Choose a Zex or NOS wet kit. They inject both nitrous and additional gas in a fine spray and alot safer on the engine. They also use the throttl position switch to activate the system. I choose ZEX weighing the features and price....... I kind of dig purple too.
Either way they dont make a kit specific for the GXP, you have to choose their univeral 8 cylinder fuel injection wet kit. The ones you posted are just that, The parts store just assigns them to most applications. If you get serious about it, I will dig up the thread showing my installation. It has pictures and where I put the nozzle. With it I bought the rapid fire purge and laser lights that beam through the purge. Big consideration is the $50-$60 a bottle for the nitrous, and it goes fast. It injects the nitrous as a liquid so with a couple of purges, you can go through it easily in a night.