If you replace the sub you are going to want to use an aftermarket amp. The stock amp will not move an aftermarket sub to make an ounce of improvement, infact you may lose volume.I have an EX-L and I hate the audio system that came with the car. I have already upgraded the front and rear 6 inch speakers with aftermarkets. I want to upgrade the subwoofer but I want to make it as simple as possible. Can I just replace the stock subwoofer with an aftermarket one whileusing the stock wiring ? I am trying to prevent having to do additional wiring.
So, install an amp that will accept High Level Inputs, tap into the stock wire in the trunk and then try driving the stock sub first. That may give you what you are looking for.
The stock sub in our odyssey is disapointing at best. I think it has the same power going to it as the full range speakers, just with the mids and lowes crossed out.