I just continue to use 4x10s, I got some decent ones and then turned the gain down from the head unit so that they aren't as high powered as my other speakers, considering that between the front and rear doors I have 4 6.5" midrange drivers and 6 tweeters they don't have to be super loud to add a little midrange to the overall audio
You know making these with 6x9 s would make so they don't stick down as far . And packed with spray foam would give them more thunder. Or boom mats . It's all about perfection . Any one know pioneer 6905s there best 6x9 I ever heard . Bass is amazing but it was a 80s thing but about $100 a pair . Played them for years . Never heard a new pair perform as well. Not even Polk .