Exhaust Sound

[FL-01.986]

New to this BBS.
2001 5-speed 2.7L Boxster.
Purchased Apr. 2006.
Love it.

Question:

At speed & when getting on it, the intake/exhaust sounds super cool (Is that a 917 coming? Just kidding.), especially in the 2nd & 3rd gear revs to shift-point!

But, when I'm just tooling around through parking lots, or through the neighborhood, there is a sound, like an exhaust leak (exhaust-bypass-like).

Is this normal, or should I have the exhaust checked?

There are no typical "Leak" smells ...

By the way, where exactly does the cool sound come from when winding the engine up? Is this a characteristic of the air box? Snorkel? Just curious.
Thanks.

[superglide]

What type / brand of exhaust do you have? Mine (Stebro Race) does a bit of that, I've noticed, and I'm thinking of pulling out the chicken-wire inserts in the twin outlet pipes. Anybody else out there have this experience?