the noise is still there after an exhaust change, so it is definately something we need to investigate further.
that was my first thought.
interestingly, your idle rpm when warm is actually a little bit low (should be 850 in an ideal world, but 800-900 is expected), and an inlet leak would usually cause a high idle rpm.
however that could still mean you have a small inlet leak, and the ecu is compensating for it by increasing the fueling and advancing the ignition, and although it is doing this well, there is still a noticable difference compared to the expected idle rpm. this leak would cause power loss when driving. rather than replacing any sensors at this stage i think its best to resolve this noise issue first.
a vacuum leak will almost always show unusual MAF and lambda readings during a diagnostic, but not neccessarily causing fault codes, which is why a code read is so crap and sensor values need to be read in real time to really diagnose what is happening.
i would thoroughly check for a vacuum leak on the intake. rev the engine while you have your head in the engine bay. check all vacuum hoses.
also check your sparkplugs are all airtight, you may laugh but this could easily be the problem. check with the engine running and the spark plug cover removed. feel for air movement around each coil.
if you get the car in a garage a cigarette can help, you'll more easily see unexpected air movement, especially with the engine getting revved