If you are only looking to add another 50hp, why not change some of the engine parts to get more power? You could probably squeeze another 30-40hp out of some changes to your engine for the same amount of money as the nitrous, except you'll have the power all the time.
Selling the Gt40 intake, could probably make up half the power, and you can probably break even by selling it, and buying something a bit larger.
Maybe a little headwork too.
I really don't think you need the nitrous to meet your goal, so why risk it.