MKIV Bora - Stock system upgrade

I having decided it would be more worthwhile to first upgrade the audio setup, and rather than suspension, i have some rather noob questions! Im more of a home/headphone audiophile, so car audio is a little out of my realm of kmowledge. Excuse the abundance of questions! Thanks first!

I know 'sound' is subjective to personal tastes, and i prefer my music with clarity, both in vocals and bass. IE no muddy single tone 'boom', if that makes any sense :confused:

So im looking to start slow and upgrade each component, due to limited finances. Currently the stock system is the eurovox + cd stacker. Car is a '03 Bora V5

Firstly, looking at a new head unit and have short listed the Alpine CDA-117. Is there really anything else i should consider around the $4-500 mark that the Alpine retails for? In terms of audio quality, 2-DIN + LCD would be an nice extra but if it means sacrificing SQ for some features I cant use while driving is rather pointless.

Now i have read that the stock VW speakers from the MKIV's are pretty decent, making aftermarket speaker upgrades having to be on the high end of things, completely putting it out of my budget.

So having thought those out, is it worth amp'ing the stock speakers? That is will the stock VW speakers benifit from an quality amp, rather than driven directly from the speaker outputs of the Alpine unit.

If amping the stock speakers will make it perform better, what unit should i be targeting not to ruin the what I read is excellent sonic performance of the Alpine HU.
- I may or may not be adding a sub, it depends on how clear or enough bass out of the stock 6.5"'s. I do have a spare 12" Vifa subwoofer driver sitting around from the last decade which could be put in a box.

Sorry for all the questions, just havent been able to find any decent information on the stock speakers if MKIV's
Thanks! Will

Just an update, went ahead with the new headunit and even with the stock speakers, the difference in clarity and bass was amazing!