Peace of mind?

[BillyG]

Hi, recently bought a 2002 2.7 and noticed a couple of noises particularly noticeable at idle when warm. First is a low-ish intermittent rumble, more pronouncable when air con is switched on. Second is a slight buzz a bit like exhaust noise (but don't think it is). Can hear particularly well through the right side air intake. Both noises disappear when revs are slightly increased at which point the engine sounds perfect.
Been told by the specialist who sold me it that Boxters often make make a bit of noise and it's nothing to worry about. Also got it checked by my independent mechanic who also seems to think it's fine. Would really appreciate some feedback from you expert owners though. Cheers!