Hi, i'm in the middle of installing a new system with an old but good Pioneer DEH-P4100 SD headunit and I'm in search for tweeters to replace the oem that apparently are missing (thats how I got the car from the previous owner. May have been missing from the start!)
Any ideas/links?

Just tweeters is a tricky one. Do you have the factory door speakers still connected?

The safest bet would be to buy a decent 165mm component set where the tweeters are matched to the bass units and connected with the accompanying crossover box. 60-100 EURs buys reasonable stuff these days which will be a fair bit better than the factory originals. They were very simple but adequate. Modern stuff can sound a lot cleaner and dynamic.

Whatever you do, you will have to fix the new tweeters to the underside of the dashtop grill.

Thanks, In the meantime I found this which should match what you are saying.
http://www.car-hifi-radio-adapter.eu/en/...ront-doors.html

They look quite tasty and cost effective. I've not heard of Helix before, but judging by there upper price range they are pretty good quality?
Do you know if the tweeters will actually fit under the dash grills?

See if you can find something along these lines:

http://www.ebay.de/itm/RAINBOW-Auto-2-We...=item3cc69e480d

Will be a significant step up from the Helix for not much more outlay. I have Rainbow/AIV Green Power SLX 165 Deluxe speakers in my Coupe from a couple of years back and they are very good and fit with minimum customizing (tweeters only). The green a is bit odd though! In Germany, Rainbow speakers were an option on the Coupe according to the brochure from 1996/7.

Focal speakers are rather nice too

Reference: http://www.hifitest.de/bestenliste/car-hifi-lautsprecher_16cm_30

My understanding is that they are all universal fitments so you have to do the adjustments or modifications for the tweeters. You may even place them on the dashboard where the dash grills are. This is a guess from my side, don't actually know if it works out but should be interesting. I think the door speakers should fit fine.

At worst, you may have to modify the mounting under the tweeter grill and heat glue the new tweeter to it. Not too difficult if you take your time and use the most appropriate mounting ring that comes with the tweeters.

I removed my original tweeters (still got them somewhere) but have now fitted separate tweeters (Canton I think) on the floor in the footwells, pointing up. They came with a little housing that I screwed using a self tapper into a small piece of MDF under the carpet. Got the idea from another forum user ages ago.

Ideally, tweeters need to be at ear level and in direct line of sight of the ears. They are mainly responsible for imaging so, clearly, tweeter location will play a big role in this. FIAT's solution of bouncing the high frequencies off the windscreen is a reasonable compromise as glass is a good reflector at these frequencies.

Floor level tweeters is rather unconventional. Do you not get an image that places the singer somewhere under the engine?

Not at all, but that might be due to my poor hearing at high frequency, or perhaps I spend more time trying to imagine what's around the next corner or what other driver's are going to do, instead of trying to imagine a sound stage and where the instruments and singers are...?

I find that the better the sound, the less I have to concentrate on it leaving the brain more bandwidth for the other stuff. In home hifi, that just means one can really concentrate on the musical content and forget the equipment. In the car, it might mean that there is more time to concentrate on the road. Maybe it makes no difference because one only really notices when one does a sound check sitting on the drive!