a engine is a air pump, the more air you can get in and out ,the more power it will make, yet the smaller the engine (like in the u tube video) the less to none it will make, also if the factory has done their homework and made the intake to flow all the air the engine can take then a aftermarket intake will do nothing.
I made and now Needswings makes a intake for the PT Cruiser Turbo, it increases the hp by 2 to 3 hp,but that same intake just clamped on a V8. (which we did ,increased by 17 hp) K&N advertizes 20 hp on a chevy 350 but that same intake on a 454 they ad. 34 hp.or there about,, this is over stock.

some real data to think about, both HP and MPG,,,,, Data from over 1000 SRT 6 owners.
The srt6 stock is ok _____about 330 hp& mpg
with K&N filters is better ____about 332 hp,,mpg+1
the 55 intake is even better____about 335 hp,,,mpg +2
the Needswings single is way better___about 339 hp,,, mpg +4
the Needswings duel is the BEST_____about 340,,,,mpg +4 to 5

some one can post the data showing the Na, as i don't have that but am sure it is very close to the above. jim