Adding bass to the Si (help)

I’m almost 100% positive that yes it will still work and depending on what kind of audio your going for you could prolly use that factory amp to power the mid’s & high’s permanently and just use amp to power the sub(s) - unless of course your putting some crazy 1,000watt subs in there then you may need a bit more power for the speaks & tweets - at that point you may need to upgrade those too
Even once you get your sub in there I believe you can still keep the factory sub plugged in/working as well just needs to be tuned down… run as much as you can from the factory amp, use aftermarket amp to strictly power sub

I don’t have a solution just wanted to confirm that - yes, these cars can be slightly irritating because you can do almost nothing without Hondata lol