Cary SLI 80 Signature Upgrade?

Try Dueland caps. I have them installed in my Audio Note L3 preamp. They sound great. They're not inexpensive though.

Ghost Pepper,
A cap that is well thought of by minds much greater than mine is the Jupiter copper foil. They are supposed to be sonically comparable to Duelund, and the price, while not cheap, is far more affordable.
I am having an amp built presently, and I had the stock Mundorfs replaced by the Jupiters. Do a search for them in the forums.

This is a bigger topic than I was prepared for! I was expecting a simple yes or no. Ha. I should have done some research before asking. I have a feeling this will take some time...I'll look into the Jupiters first.

Live with the unit stock before you contemplate any upgrades. You need to understand and appreciate the unit's sound signature for a period of time before you attempt to modify the unit. Not all "upgrades" are sonic improvements.

I asked for cap recommendation for my Sli-80 F1 on the amp forum at the Audio Asylum site and got quite a range of recommendations. It's an interesting group with a lot of DIY experience that hangs out there.

I went with the Cardas caps, which are no longer in production but can probably still be found. The Audio Connection in Seattle had them a few months ago when I had the work done. I don't know if they sell them, though, John may be saving them for his repair business. He likes them a lot and recommended them very highly. He'd bought a large stock of them when he heard they would no longer be produced.

I agree with the recommendation to just listen for awhile before you start upgrading. I did the swap because one of the original Jensen paper in oil caps failed, not because I was unhappy with the sound.