As my car is very loud with the single exhausts, small rattles or noises can't be heard, for a couple of days i've been hearing clicking noise from the rear ... the clicking goes faster as i accelate faster and slows down when i slow down but its always there and matches the car speed, it sounds like metal knocking or grinding ... but today after a looong drive the ABS light turned on and clicking became louder and loud enough to hear it over my single exhaust!! the ABS light goes off when i drive hard and normally after 170kms/hr on my speedometer ..... i tried reversing and i couldn't hear the clicking sound, so i assume its only when i drive forward .... any suggestions???

 

Any vibrations?
What side is it coming from?
Could it be something stuck in the tyre?
Have you visually inspected the wheel/hub area and possible the drive shafts?