Im commenting on this thread after many years it had been abandoned.. btw, my myvi lagi best never had any speakers replaced or changed, everything are stock speakers, HU, and all. Not even an underseat subwoofer installed. But the bass it gives now is nearly amazing. I said nearly because it doesn't produce enough lowest bass range as much as I want that it vibrate my butt. So how did I do it? You only need to tweak the sound setting in HU. Set max bass to 7 and treble to 2. Then I suggest you don't play songs from radio, use any pendrive you have and put your high quality favourite songs in there, then bam! Everything sounds clear and a bit bassy. A bit? Yeah, it will only be a bit bassy, not until you go back to setting from home page, and set the bass to 7 and treble to 2 again. This will cause the HU to overlap the max bass setting, hence causes the settings for bass to become double the bass than what the max bass setting should produce. In the end, you got to play songs using pendrive with a super bassy sound produced from your speaker. But then again, I suggest you do some sound deadening on your door especially the metal panel inside because this will improve the mid bass a lot more. Dont forget to soundproof any rattling sources.