Just because some vehicles have shown some horsepower increase does not mean it will for his particular application. You dont know his altitude, health of the engine, etc. I'm not saying it's a crappy product, I'm just saying you don't know what the dynos used were and how accurate and maintained they were as well.
Plus, why would you waste money ($330 USD)on an intake that may add 10 hp if you're going to be adding a bunch of weight with heavy stereo equipment. He wants more space for an extra battery, not to run better times at the strip.
I know plenty of what I am talking about. I'm just using logic rather than some anecdotal advice based on dyno proven results. Yes, several guys may have had a hp gain, but there are so many factors including other mods at the time of the dyno run. Even their website doesn't even show a dyno run.