Upgrading Fuses

Just upgraded the fuse in my integrated amp. Didn't change the world, but did make a positive difference. Well worth the $40 spent.

They work, but it will depend on the resolution of your system to determine just how big an improvement you'll experience. Expect to be disappointed for the first few days as they, like anything, need some time to break in. I kept my system on for 4 straight days at a very low setting and from time to time would check in on it.
It went from 'what the hell is going on here' to 'that's very nice indeed'.

"All advice appreciated."
I think they are selling mass production fuses with gold(ish) plating on the ends & some fancy decals and packaging.
That said, if you can just buy one fairly cheap & see if you think it makes a difference, what the heck.

I think they are selling mass production fuses...

Maybe with some makes but the HiFi Tuning fuses I use are made of ceramic instead of glass, to control resonance, use silver wire, and are cryo'd. It's not snake oil.
There are enough reviews out there from 6moons, PFO, Stereophile, and Stereo Times, to name a few, that think very highly of them, not to mention enough testimonials from us average Joes (and Janes) to start a blog.
Check out the other threads on this and go with a reputable make and you won't go wrong.

Nonoise - A quick search for something like "fuse construction" will show you that ceramic mass production fuses are very common, use of silver in fuses is not particularly uncommon, the value of cryo treatment and the validity of testimonials are probably things that we weigh very differently.
It is a little off track, but I think that any audio product concept that appeals to audiophiles will eventually result in glowing testimonials of whatever product is developed. If you could develop convincing pseudo science suggesting that dried elephant dung absorbed emi, there would soon be much of it sold to audiophiles and history suggests that it would eventually be cryo treated and encased in silver mesh webbing by some of the more creative vendors.
None of the above is relevant to the question at hand though, I'm sticking with 'if you are inclined to try it and it is cheap then what the heck'.
Happy listening!