Here's a good rule of thumb...if the product name contains the word "NO"...as in Nitric Oxide...ITS A LOAD OF HORSE ****. NO/NO2 products are just fancy forms of l-arganine.
there is ZERO scientific evidence to support any claims that NO2 products help you lift more weight, help with endurance, or help with muscle gains during recovery.
the ONLY scientific fact about NO2 is that is does dilate blood vessels/muscle tissue, allowng more blood to flow in, which provides you with a 'fake' pump...as opposed to the 'real' pump you'd get by slinging around some weights for 10 minutes...plus it costs more.
That said, NO2 products are great for giving you a rock hard erection, and if you look at ANY of those supplments that promise to increase ***** size, you'll find L-arginine (or one of its forms) listed in the ingredients.
In a nutshell, its a waste of your money. It does give you a cosmetic pump...but it doesn't do anything useful except putting more wood in your johnson. you can get ALL the same effects by taking normal L-arginine for a fraction of the price.
Remember, 99% of all supplements are 100% hype, 0% effective. NO2 is just attractive because you can see and feel the pump, so you think its doing something...when it really isn't.