5watts going to an 8" vs. 5watts going to a 10" - the 10" is going to be deeper.
Is it going to beat a 10" driven by a Hifonics MAXXIMUS? No (duh!).
Is it going to beat an equally powered 8" Yes.
As long as the 8" and the 10" have similar specs, the 10" is going to go win with everything else being equal. It moves more air (due to its surface area) than the 8" does.
In my perfect world - nothing in the audio system would be OEM. It would all be aftermarket and every set of drivers would have its own amp.
In my
real world - the OEM is fine except for the very top end (going to drop different tweeters in the pods and mids in the doors) and the very bottom end (not sure what my fix is going to be yet). I am not after tons of volume or super audiophile clarity, just better overall freq response.