Elise S1 fitting a cone filter

[Fabio81]

I was tired of the sewing machine noise of my Elise S1, so today I fitted a cone filter, hoping to improve the noise.
I'm not a mechanical guy, so 2 questions arose while fitting:
1. I only removed the top half of the original air box (and the original paper filter of course), is it sufficient for correct air flow?
2. tightening of the jubilee clip can cause sticky throttle issues? While revving down the motor seems to be a little hesitant around 1500rpm but quickly goes down. Haven't had the chance to test on the open road though (just revved up in the garage). On the other way if the jubilee clip is too loose i fear the filter would come off. What's your suggestion?

Thanks!

[Fabio81]

Update!
I tried the car on the open road and it makes a beautiful sound! :-)
But another question came to my mind: the cone filter is directly under the grills of the engine cover... would it be a problem if it gets some water? (rain, or washing the car)

Thanks!