First of All Europa, I have to (collectively) thank you for the effort you put in your document. I was really pleased and positively surprised of your results.
Now on the technical side...
I, like you, opted for not changing the original Head Unit (My mrs also drives the car and does not want to change the look & feel of the dash with an aftermarket HU, regardless of the improvement in sound). So the only way out to improve the sound was to go for the TS-Q131Cs.
In my case, and out of impatience and (ignorance) I bought a pair of Alpine E-Series speakers, guiding myself by their brochure that suggested them as a direct replacement for Renault Megane front door speakers. Once in my hands I discovered that I had to
a.- Cut 2 out of the 4 speaker mounting brackets
b.- Cut off the weather shield...
Only to discover that the sound did not improve much and that I had a nice pool in my door bins!
Luckily, the technical assistant at the product design department at the University where I work was able to help. He made me a pair of vacuum molded pastic weather shields that we put in place using some hot glue and finished off with duct-tape (just to give it more strength) ... Lesson Learned: Research before you cut.
After that experience, I just went and ordered a set of TS-Q131C. The improvement in sound was much more than what I expected. Really pleased.
Now Im struggling with the rear doors...
Ive read posts where people say that they just wont bother with the rear speakers, citing various reasons; from "i dont seat in the back therefore I dont care" to "I barely hear the sound coming from the rear door speakers". In my case, I believe that there was such an improvement with the new speakers that its a shame to keep the fade all to the front just to "avoid" the bad quality sound when I could 'repeat the experience' in the back too...
Yesteday I started my project of stripping the rear doors (and you've inspired me to document it
) As you know, it is by no means as straight forward as the fronts, but Ive been bitten by the TS-Q131C bug already and would appreciate your opinion on this (project of replacing the rear speakers too)
Thank you for reading all this!
Alonso