[schmove1]

If your bass cuts out, there are a few things that could cause this: 1. Bad ground 2. System tuned incorrectly and amp clips and shuts down to protect itself 3. (Still has to do with tuning) Factory variable signal has significant bass roll off and was not adjusted or addressed during system tuning. (Factory bass signal is reduced at higher volumes to protect the factory paper speakers; referred to as bass roll off).
All of these items should be addressed by the place that installed your system, since they did the work and know how they did the install.