I recently started hearing a clack clack clack sound when i accelerate at low rpm's at higher rpm's around 3-3500 exhaust drowns out any sound. The other night i was cruising around bored and a street bike and i were slowly cruising side by side messing around i dropped to 2nd from 3rd at around 30mph shifted into 3rd then let off. At the light i took off normal and the sound was really loud now. Could it be the drive shaft? Mods are CAI, shorty headers and bbk o/r h.