Your only going to get a clear concise answer from a scientific study and that's only if all things stay consistent. As a performance firepower ignition kit owner I will say the product looks and feels beefier than stock (fact). As far as power increase, I did not do a study, so - a bit smoother and responsive over stock - not kick in the pants noticeable (conjecture). I use the champion #4412 truck plugs as recommended by others and like them (opinion). I gapped them at .065" (fact) and see no problem (opinion). I'm happy with the install and my purchase (opinion). I needed a tuneup when I put them in so I don't know if a plain old tuneup would feel the same (lack of knowledge)
. The combo makes me feel like I used the right product so I'm biotching a lot less about the cost (truth). I believe it contains a little less snake oil than Jet chips (truth) okay (opinion).
If your looking for someone to say this is the best thing since the invention of toast and back it up scientifically-well I got a 35 horsepower gain CAI and a 20 horsepower gain throttle body spacer that has been proven to raise your horsepower to 4.0 levels for sale. Read what others have said about them here and elsewhere, check your pocket book trust your judgment. Good Luck.