I picked up a vintage Yamaha SG2000 last year.
I'm in a bit of a dilemma as well, on the question of the pickups. I actually quite like the stock pickups but I know deep down that a set of the right BKP's would almost certainly turn an already awesome guitar into a mega awesome guitar :D
There are other considerations to think of as well though.
Because the guitar has a particular style of pickup holder/rings any change of pickups will fundamentally alter the look of the guitar - unless Tim could make a Yamaha type pickup holder and ring :P
If I did go ahead and swap the pups for BKP's, I'd be looking at pups that could handle the large amount of maple that the guitar has and the natural 'tight' snap that it has due to the neck through design. I'd also be looking at a mid/high(ish) output set of pups as well, as the stock pups are also mid/ high(ish) output.
If you've followed this so far you're doing better than me :D
Here's my thoughts on BKP's for my SG2000.
If I didn't already have a set of Emerald pups in my LP I would seriously consider them. They have warm bottom end, punchy midrange and a real bite at the top end when pushed.
Mules would be a safe option but it would possibly lose the character of the guitar? It's an odd thing to say I know, but I'm not putting Mules down - far from it. I think that in a LP they provide an awesome vintage tone but IMHO the SG2000 needs something different to suit it's unique characteristics - neck through design, lots of maple, ebony fretboard, brass sustain block etc.
With that in mind I would consider Crawlers or Holy Diver pups as viable options.
I'm open to thoughts on that - as I'm sure Cat is as well.
Piccies of my SG2000 .....



