We have 6 Polk db651 marine speakers as as well as a sub on a 2014 Malibu Ski Boat. For a non enclosed area, they direct sound quite nicely. Probably the best sounding speaker I have heard for its size. They will also handle more wattage if you decide to upgrade the head unit (amp) down the line.
Polk db651's are an awesome choice.
My new favorite speaker is the MB Quart Onyx line. They are not exactly the same as the old school German-made Quarts from back in the late 1980's and early 1990's. Nowadays Quart is made at the Maxx Sonics factory in China but there is still enough of the old original German influence in the speakers to provide excellent sound quality. I recently put two pairs of the Onyx OKC116 6 1/2" speakers in my truck and they do sound very fine. They have a nice natural bass and midrange response for an entry level speaker, and the tweeter is the smoothest I have heard in a long time, it adds a very sweet component to the overall sound experience. Amazon sells the OKC116 for $45.00 per pair:
I have my 116's connected to a Pioneer MVH-X370BT digital media receiver and they do sound great, but they would likely do very well on an OE Honda system too. The only downside I found with my new Quarts is they are a tad less efficient than my old Pioneer speakers. The Quarts are just a little quieter at lower volume but I compensate by using the Source Level Adjustment on my deck as kind of a preamp volume, or I can just turn the main volume up a little.
MB Quart may have changed hands a time or two since the 80's but the spirit of the old German sound engineering is still there. The sound is very realistic and musically accurate without any of the coloring and shrillness found in so many aftermarket speakers. Quart is definitely worth a look and a listen.
