Should I mix Polk DB651 and DB651s or DB651s all around? What benefit, if any does using DB651 in rear give vs using 651s. Any advice?

save the money, the rears make little difference to the driver.

Im sorry, but I fail to see a difference between the 651 & 651s. They are both the same price on Polk's website & look identical.

Or were you talking about the 6501 (components) for the front & 651 (coaxial) for the rears? If so, that would make for an excellent sounding setup.

Otherwise I see no reason for picking between 651 & 651s, they are the same price so get matching.

DB651 will fit in front but need some grill mods to factory cover so tweeter fits. I don't feel like dremeling factory grill covers, so it will be DB651s in front, Just deciding on rears.

Im sorry, but I fail to see a difference between the 651 & 651s. They are both the same price on Polk's website & look identical.

Or were you talking about the 6501 (components) for the front & 651 (coaxial) for the rears? If so, that would make for an excellent sounding setup.

Otherwise I see no reason for picking between 651 & 651s, they are the same price so get matching.

Here you go, now you can see the difference!!

http://www.polkaudio.com/images/global/car/slim.jpg

If you can get the 651 speakers cheaper than the 651s pair, then get the 651 speakers for the rears!!

Learn something new every day, thanks for the pic.
Looks like the 651 not only has a taller tweeter, but also a taller surround (more cone travel?)

You dont need to dremel the grills, there is an easier method for removing plastic ribbing.

Run a razor along the base of the rib(s) to score it, and make slits in the rib every inch or so depending on how much you need to remove.
With flat tipped pliers (the wider the better) grab the rib & just twist it off. The rib will break off at the score & it will be quite flush, and only takes a minute. Ive had to do this to quite a few cars.

(edited for late night spelling. lol)

I dont think it matters which you go with in the rear. As long as you are sticking with the same brand and series of speaker you are fine. I never recommend getting mismatched sets, for example infinitiys in the front and polk in the rear ore vice versa. they have different "types" of sound and dont generally compliment one another well if at all.

I was thinking by going with the DB651 in rear because it fits without grill mod, and that speaker has a wider frequency range and more power than the DB651s, I might get more bass, but I'm not an audiophile. Also any thoughts on CDT CL-6EX?

Decided on getting db651s all around, found new open boxes for $45 a pair. Waiting on new HU, Eclipse CD1200G, and speakers, and will post with photos and a review.