The problem is that right before VTEC engages, it sounds like there is hollow, low pitched echo with a similar note as VTEC. I wonder if its a wheel bearing or a carrier bearing from the diff going out. I've checked the motor for any problems, oil pressure is great, compression is good, oil has been changed (no metal), my clutch is fairly new (under 10,00 miles). Axles are brand new, tires and wheels are new. Happened before both of the above. Any ideas?