After some pondering I've decided to get a new wiring kit for my SG Faded, but I'm having some problems and questions which I hope you all can answer.

The kit I'm looking at; RS Guitarworks Premium Vintage SG® Electronics Upgrade Kit, seems to be great on paper and has quality components as far as I know. But it also says that it isn't suitable for people who experience harsh tone, which I do. I know for a fact that it isn't the amp (I've tried a few), but I get really high pitched harsh tones on both the neck and bridge pickup.

Here's how I'm thinking regarding the problem:
SG Standards usually have good tone, and not overly bright, and they use 500K pots. The treble tamer kit (the one they suggest to use if you have harsh tone) uses 300K pots and a slightly lower cap value. If I were to switch to a Premium Vintage SG kit, with the 500K pots and slightly higher cap values, do you think my harsh tone still has a chance to go away or would this make it even worse? What boggles me is that there are loads of Standards with 500K pots that don't sound harsh, so is this a matter of pot quality or do some guitars have significally brighter/harsher tone that forces people to use the treble tamer kit instead? Also, IF I get the treble tamer kit, will the harshness go away and instead give me a dull sound...?
Gibson SG Faded (Gibson Angus Young Signature humbucker)
Epiphone Valve Junior Combo V3

Marshall Bluesbreaker BB2 pedal