New much better speakers not much better, help

I put the same in my little travel trailer. They sound better than the no brand junk the factory put in, but they're full ranger drivers, not woofers. Can't expect that much bass. Car stereo probably has 6x9 in the rear for bass boost.

I also put in a 8" Pioneer sub in a slim band pass box, and a 200 watt 4 channel Pioneer amp with dual crossovers. Two channels for the drivers and 3+4 bridged for the sub.

Head unit is a cheapo Pioneer something something. Using the preamp out.