Mine does it a bit when your just setting off, in fact i got accused of having a turbo conversion by old subaru mates :shock: ( but thats cos they couldn't shake me on the B roads )
all is normall. its just your highly restrictive paper filter truggling.... you need to get at least a panel filter k &n style....will free up the car and improve smoothness of acceleration and down shifts....
Ooh boy, are you gonna get some varied replies, everything from temperature sensor-less driver door mirrors to standard air filters, the truth is it's the cars soul, the faster you go, the happier it is, so it whistles a tune to let you know it approves of the increased pace. Then when you're driving fast enough the whistle is replaced by a roar. That's when you know you're driving at the correct pace, when the whistle can no longer be heard.
The most plausable reason I've seen is that there is a butterfly valve in the standard induction system that causes the whistle, the noise will disapear if you fit an aftermarket induction kit.
no they improve...i fitted a k&n from ebay ......very very highly reccomended!!!! make sure you fit a cold air feed to the floor as the standard one you will have only goes above the horn... a good foot from the floor