I humbly question the 10-15hp gain from those components.
Now let's say the car had spark plugs so dead the car could barely idle, the air filter was clogged, fuel injectors so gummed up, ignition wires with very weak conductivity etc.... I can understand the car getting back to a healthy state like it should.
However - to gain those ponies with these simple mods - I have my doubts.
I haven't reviewed the article in awhile, so if I'm wrong, let's just say denis is buying the drinks...
I think it's the old aftermarket (well, dinan --I'll come out and say it) HP gain thing: take a built up engine (or rather, an engine with a supercharger lol), do some mods, put the thing on a dyno and say, "we got 10hp on our car, on a dyno, with these mods".
but extrapolating those gains back to a stock engine, etc etc. its like, 40% of their gains. But, in the ads its like, "this kit gave us xx hp gains on our test car").