My 99 T5 has about 210k miles on it - began making a low end rotational noise that sounds like a 500cc dirtbike motor when it's winding up. I've replaced front wheel bearings 60k ago, still has original cv axles. It's not connected to the rpm, but goes higher in tone with speed. I've even put it into neutral @ 55 mph and revved the engine to confirm it is not anything with the motor, doesn't change with the revving. So drivetrain me thinks - typically I would expect a whine from bearings, but this is too low? CV axles I would expect a clicking under load like when you power around a corner or circle under load in a parking lot, but these don't change the sound. Tires are new last year, less than 20k on them. Rotated fronts to backs - didn't change noise.

I'm down to guesses here: maybe a wierd cv axle noise? if so I'd be thrilled!
Maybe the carrier bearing on the long axle on the passenger side? Maybe the trans bearings where the axle connects? It could be my imagination, but the noise seems to favor the right side. You can almost feel it through the floor boards - HELP!?! Sam from MN.