If you are still hearing the sound dip then then Navboot is still patched.

You need an new unmodded OEM navboot (thats never been patched), if you had mods to the nav boot then you will need to re-apply them but just dont add the patch.exe.

__________________
Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.