I don't know about adding speakers to a stock system. (Power output and speakers are likely optimized.) Add a small amp to what you got and/or, better, amp (many with built in crossovers) and speakers. That'll change your world.
Easy fix, if you're content with the sound and volume of current system is to add a powered sub in the trunk (with remote output control - 'woofer volume'.) That'll add some real depth to any system and can be had off Amazon for a couple of hundred bucks. Did that for my son's accord (12" powered sub...Blaupunkt or Alpine, dont recall) assuming Honda/Acura factory systems are of similar capability and quality, it's a gamechanger for sure.
I didn't look, and am not familiar with the upgrades you referenced. I just had a minute for some stand alone, general theory advice. Ha