Increased induction noise - linked to misfire?

[sbloxxy]

I have a 2000my Boxster S with manual 'box. I've owned this car for around 8 years now and one of its characteristics is that the induction noise is always slightly louder until its warmed up. I'm guessing all Boxster S models are the same? Anyway, recently this characteristic has changed and the induction noise remains rather louder, even when the car is thoroughly hot. On the one hand, its quite nice as it sounds terrific BUT I have also noticed a slight hesitation when changing up a gear at full throttle. It may be my imagination but fuel consumption also seems a little worse than usual too. Does any one have any ideas? Or am I imagining things?

[Steve Tinker]

1) Has your car had the "snorkel" removed from the inlet duct behind the L/H/S air inlet?
2) Have you checked the condition of the air filter?
3) Have you checked the inlet pipe (filter to throttle body) to make sure its still attached, tight and / or not broken?
4) How do I say this without being flamed by a forum expert - do you have an oiled aftermarket filter? You know, the ones that have to be oiled which affects the MAF or lets dust and contaminent's in if you don't oil......