2000 VW beetle with 130,000 miles. I just replaced the rear shocks and shock mounts and now I have a loud banging noise when driving over bumps (it even makes this noise when you sit down in the seat so it doesn't take much of a bump). Any thought on what this might be? the noise didn't exist until I changed the shocks. I didn't replace them with expensive shocks so maybe it could be a defect with the new shock?