I have a 2009 Acura RDX with 2 bad speakers. I am replacing one of the fronts but the speakers are cheap. Really Acura?
Tiny magnet, right? My 2009 CR-V had similarly "cheap" speakers, but keep in mind that with the race on to improve gas mileage, they made these speakers to be ultra-light first, and put sound quality second. Then again, we had a horrid Bose system in our '99 TL and those speakers were flimsy, cheap paper cones (no tweeter, no whizzer cone) with small magnets and flimsy stamped baskets, cranked through some extreme equalization through them to get the speakers to reproduce frequencies they just weren't designed to handle. So even a "premium" system can have crap components.
I put Morel Maxximo speakers in my CR-V--a 6½" component set in the front (due to dash-mounted tweeters), and 6½" coaxials in the rear.
However, I did this as part of a total system replacement, so I am driving them with a separate power amp on a Pioneer head unit now. I did not use them on the stock head unit. And I had to use EQ to knock down the front tweeters quite a bit since they were way too bright. Tried a Polk component set, but they didn't fit--the shape of the woofer basket would not clear the opening in the door. So, that is something to watch for.
The 4-ohm speakers won't hurt, but the sound output will be noticeably less, if my past experience is any indication. I had cheapo oem Pioneer speakers in my '97 CR-V, and dropped in my old Polk MM-series speakers. They sounded better but could not play nearly as loud on the stock Honda (Alpine) head unit since they were not as efficient. I have no clue as to the impedance of the original Pioneers.