Check the ground cable and see where its grounded to. Also what size of power and ground wire was used?
What is the gain set at for each channel?
2006 BMW 325i Titanium Silver
Mods- 19" AG M310's hypersilver, drilled and slotted rotors, OEM rear spoiler, OEM exhaust tips, corner delete mod, carbon fiber wrapped trim, Viper 5904 Alarm + remote start
Audio upgrades- Alpine S920HD, JL XD600/6, Jehnert XE200, Morel Hybrid Ovation II, Audioque 2200D, 2 Alpine SWR 12d4's (forward facing sealed from trunk)