Two questions......
 

I have a 2005 coupe. That I have upgraded with a full exhaust.....ARH headers, three inch X pipe , and Corsa Sport level exhaust plus an E-Force Edelbrock supercharger using a smaller (12 lbs boost) giving me a Dyno at 640 flywheel 590 at the wheels. It's fun to drive and WOT never gets old but I was wondering if it would be wise to add a NOX unit. The one I'm looking at is a hidden system and only kicks in at WOT. Small bottle can be hidden in back. Plus I read somewhere (can't find it for the life of me)
that there are high performance throttle modules that give much better response both up and down. If anyone knows where the heck those are being sold and if they are all they say they are I would really appreciate a hint of where to look. Soooo I need to know if NOX is a reasonable option and the pros and cons from some users. I think I would probably use a stepper that allows for 30 to 100 injection. My car looks like a standard 345 horsepower coupe so I am aiming at being a perfect sleeper. E-Force stays under stock hood and ya can't see the exhaust setup so I want to keep the NOX unit under wraps too. Any help would really be appreciated.

I have a couple questions, your flywheel to rear wheel loss is the smallest I have ever seen and how do you keep the diff alive since it is a 2005?

Question one is because I have 650 at the flywheel and 535 at the wheels.

When your "upgrades" end at the power you create, you can expect to be replacing lots of other components. You might think about that first.

Don't know why you would want to introduce NOx into the engine, n2o would be better. BTW, at the levels you're at now your diff is on borrowed time.

Look into a Snow Performance Methanoll Kit or use the n2o to cool the intercooler.