Door speaker size/dimensions
Reply #7 –
In regards to the mdf spacer ring, it'll handle having speakers screwed into it. It's often what the pro's use when making custom surrounds and enclosures and such. I've even had a friend use it in his car due too the same reason of the speakers being to deep for the speaker wells.
Now as for the having to much distortion on the front speakers there's and easier fix than using the crossover boxes. Take a look around crutchfield.coms website for inline bass blockers. They'll do exactly what you want and are a heck of a lot easier to install. And if you can't afford or wait for them, they can be built very easily. Just takes a little bit of shopping for a few pieces parts at a radioshack.