I have the infinity system, easily add a 300w amp and boom box under the back seat. 2 10" woofers, w/ tweeters and mids, along with an EQ.
Easily added to the stoack system, not sure what the make is, but can find out. They make an adapter/harness that connects to the indash infinity and the rest is history. Easy! and no strange noise or buzzing. Just kick ass sound. Highly recommend the EQ for the boom box, was just too much w/o it.
I'll look into who makes the adapter and post it.
The speaker box can be custom ordered to fit perfectly under the seat.
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99' Quad Cab, 4x4, Auto, 3. 55, All options except fog lights and leather, Glasstite topper, Chrome Nerf Bars, VA CPC, Boost Mod & elbow, DiPricol EGT & Boost Gauges Pillar Mount, K&N Air Filter**, Turbo Silencer Ring Removed, Infinity sound w/pillar tweeters, 300w speaker system under rear seat, Metalic Red. Hum, transmission mods and injectors next? ** Removed K&N Replaced w/ paper filter - problems w/ K&N