capacitor upgrade

I don't understand why you want to change from non-polarized to polarized, don't need to. Also, film caps, which are a worthwhile upgrade, are all non-polarized.

Mundorfs are non-polarized, forget the whole polarized thing.

Other film caps to consider:
Mundorfs-all models, great extension on top, very high resolution
VH Audio V-Caps, even higher resolution, very even-handed tonality, pricey
Jantzen Z-Superior Copper-the best 'price conscious' cap I've tried, actually very good at any price, great extension on top
Duelund VSF Copper- best of the best, totally natural, just sounds like music, pricey and only come in lower voltage ratings

The only thing you need to watch is voltage rating, make sure it is high enough for application. Coupling caps in CD player shouldn't be a problem as these are likely low voltage, any of these caps (or other film caps) should be fine. You'll find present voltage rating on Wima caps.

Duelund is the smoothest, most natural hands down. Doesn't have thick mids, just natural, no colorations I can detect. Duelunds have won every cap shootout I've seen, out of this world priced Audio Notes only cap in contention for top honors. You can't go wrong with the Duelunds, problem is affording and fitting them.

The good Audio Notes I'm talking about are more expensive than the Duelunds.

I assume you have two coupling caps to replace. In lower price range, Jantzen Z-Superior Copper is best I've tried. Next lowest in price, Mundorf Silver in oil.

And if your serious about wanting a 'thick' mid, try the Audience Auricap, most bloomy mids I've heard, relatively cheap as well.