PK, ayaw mo magcomponent sub and amps? Mas preferred ko yun ganitong setup kesa amplified(no offensse just a matter of preference). Check out a 10 inch JL W1V2 OR JL W0, married to an alpine MRPT220 which pumps out 140w at 4ohms in mono mode. sakto sa 150w na kelangan ng W1V2... The preferred box size I think is around .65 cu ft lang so I see no issues on space. JL subs dont need large enclosures to sound good. The subs would cost around 6 or 7k and the amp is 4 to 5k I think... and box construction won't set you back 1k, baka mas mura pa... not sure lang how your existing wires are configured though. my expereince with JL has been great with the w6v2 and w7, never looked at any other subs since... but ultimately your ears and preference would prevail, its up to you which sounds best