SRT6 came with one of two options.

Infinity system with out Nav which utilizes a 4 channel amplifier feeding a set of MMD components in the doors and a pair of dual coil subs behind the seats.

The upgraded system swaps out the head unit for one that has navigation and uses the same speaker and amplifier system.

The Limited uses the same options with the exception of the entry level black on black manual trans model that simply used the non nav radio and door speakers