id use the 1.6k to add a cheap 4ch amp and change all 4 oem speakers to coaxials.

unless what u are looking for is to add bass to the oem system, then better off getting an active subm the kind u can put under the seat, cost about 500-800, balance can change front speakers...

still got in the market ka? havent seen any for years.....a good box made from 3/4" wood still performs better than thin plastic tubes..