I dont buy into most of those claims made. Most are unsubstantiated numbers, and they never disclose everything, or dont use the proper controls when conducting tests, in other words, too many variables. I've never seen anyone show honest to god dyno pulls, of before and after with throttlebody spacers, aftermarket cold air intakes, etc, and configured as they would be used in real life. The companies, if you believe them, well I should be able to add a flowmaster, k&n cold air system, magnets on the fuel line, royal purple oil, and put a honda TYPE R badge on the back of the jeep, and gain 150hp. Oops, forgot the spacer, lets make it 180hp now,lol. Reality is, there is a psychological improvement, but nothing solid in proof. If you took the typical ricer honda civic, with their "intake" on it, and duplicated real world conditions, ie, drive it around town, getting the underhood temps up to normal, especially with the tricked out header to make more heat, and then threw it on the dyno and checked, the high school kid is gonna cry when he sees how much power he actually lost.
Do a search on here about the spacers, and decide if you want to take the pepsi challenge. Its only money.