Returning to the web I found that the speaker 6 1/2"(170 mm) are fit with Spectra 2005 .
You could visit this site http://www.crutchfield.com to see all the kind and size that fit with Spectra.
Hope that will be useful
Actually, the rear spaekers in the 2005 Spec5 are a little used size: 5X7 inchers. It's slowly growing in popularity and your starting to see more Hyundai/Kias and Chrysler products with them. Still not many available through the aftermarket, though. Crutchfield does have a variety, and yes, the fronts are 6 1/2"
I can assure you that you can FIT 6.5" speakers in all the loactions. BUT for the doors they need to be SHALLOW DEPTH speakers, like Infinity's I put in my spec5. I just used the shallow ones all over since I wanted a matched set.
In the front you will need to be handy with making your own mounting brackets in order to get them good and secure, otherwise they will mount but not very well. I would recommend 1/2" MDF which will give you clearance between door skin and the window will have plenty of room. You will also need to cut down the plastic on the inside of the door as it may hit your speakers, Dremel tool baby.
For the rear speakers they should bolt right into the stock plates, I did have to make new pilot holes but no biggie. It's easiest to remove the whole speaker plate from the car to do the work, just a couple of bolts and it's out. Again you will need to grind down the plastic on the cover pieces, I took everything off except the very outer screen. BE CAREFUL these pieces are very thin and a little slip will leave you with a hole.
As far as wiring goes I would recommend simply soldering directly to the speakers I ordered the adapters from crutchfield and they did not fit.