i have a 2000 zx3 with the mtx-75. the humming has been developing over the last week and a half and its gradually gotten louder and louder to the point ive parked my car until i figure out what's going on. the best way i can think of to describe it is that it sounds like i have huge block tread mud tires on the focus. the pitch of the hum increases and decreases depending how fast im going and is always present whether the car is in in gear or in neutral, under heavy accelleration, light accelleration, light braking, heavy braking, it doesnt matter. ive had a few wheel bearings go bad so that was the first thing i checked when i first noticed it. they are fine. i have torsen LSD and im beginning to think that may have something to do with the sound. i also noticed a little over a month ago that i have developed a very slow transmission fluid leak. parked it over white concrete and it only ammounts to a drop on the ground every few days so i doubt thats relevant. tranny has less than 40k miles on it, LSD maby has 5000 miles on it. i also got a fidanza flywheel at the same time as the tranny and LSD. i just want this sound gone if it is due to something wearing out and going bad. ive never had LSD in a focus before so if the sound is natural thats fine. any ideas?