I am currently happily running the following system in my 97 Integra. Polk MM465 in the front 602A's as rear fill and one DX12 in a sealed enclosure. The Momo fronts are powered by a JBL BP180.2 Amp and the reasr fills HU power. The sub is powered by a JBL BP600.1. My question is what effect would it have to add a second DX12 in a sealed box to the system?. I would still power both subs from the same amp.