does a K&N air filter make the car louder?

[softinthehead]

got a K&N filter put on the 968 at the 12K service last year, when I also had a janspeed exhaust fitted. Obviously it was LOUDER! I love the sports box, really makes the car sound much more as it should, though at times it is perhaps a tad overwhelming....
anyway for various reasons i had a standard paper filter put back on at this service. on collecting the car it sounds quite considerably more refined. its still way louder than a standard exhaust but somehow more bearable.
So either i'm going deaf, which is a complete bummer considering what ive spent on hifi over the years, or the filter change has made a difference to the decibels. which is it?

[softinthehead]

yes, i'd heard that about them on PH. of course I also heard a number of voices in favour. on balance I've got more than enough performance for my needs already so i thought why take the risk? wasnt expecting a spin off with the decibels though