So the Focal are 4" 50w rms
The Audison are 4" 40w mids.
The rainbow are 30-60RMS 4" components and
(what I found were) the coral are 240w RMS 6.5" components.
Which model amp is that SPL? I wouldn't plan on using the amp on the 4" speakers. I would buy a head unit that does 40-50w RMS per ch, and play them off of that. I would definitely pick the Rainbows over the focal and audison, just because those are components. It depends on how you want to set up your vehicle though. If you're in Finland you might have a smaller vehicle with a smaller soundstage, and not be worried about how the speakers sound while sitting in the back seat. The Focal and Audison are nice speakers, but if you don't plan on running a sub, that's a lot of midrange.
If that was me, I would really want to put the Coral's up front. I just think those are going to be your best speakers. Depends on:
1. If you can find an adapter or cut it larger and make them work.
2. What about your amp? Is it a 4ch amp, that you can bridge to 2ch and use it on just those, or is it a 2ch amp that pushes about 120w rms x 2ch?
- If you can't get the 6.5" Corals to fit up front, I would definitely put em in the back if they fit, and either use the amp you have if you can get the power ratings close, or you might need an amp for just those.
FOR THE FRONT - if the Corals are in back, then you want the other components up front. You can find adapters to make 4" fit in a 5.25". You can find have rings that will mount your components in that 5.25".
If you can get the Corals up front, then you could put anyone of those sets in the back to enhance the front. Again, I would just use a simple adapter to make something fit. You will see what will work, but just run the rears off the 50w x 4 (RMS) head unit.
If you just don't want to spend any more money, and can't get the amp to work with the corals, then run the Rainbows up front, and either the focals or audison in the back, and get a head unit that will do 50w x 4 and don't even bother with the amp.