I just scored a 2008 Made in India Squier Vintage Modified Strat for $80 last week and have been trying to make it my own. I recently modded the wiring to be able to run the middle and bridge pickups in series and bypass the middle pickup's tone pot, to lessen the load the pots place on this setup. I have this wired to a DPDT on-on mini-toggle, so I can revert to the stock sounds anytime.

The result is thick and beefy, I'd liken it to a super hot P-90, and eliminates most of the quack you hear in parallel (stock) mode. The problem I'm having is that even though there is more low end, and more mids, I feel like it completely neutered my high end. I've double- and triple-checked my work, and everything is wired up as it should be, but with the tone knob bypassed, the best way to describe the tone is that it sounds like the tone pot is rolled back some.

I'm speculating this could be due to the 250k volume pot and the hot Duncan Designed pickups (a 12.21k bridge singlecoil?!?). Hard to say though.

Would swapping to a 500k volume pot with the option to switch on a 470k resistor in parallel give me closer to what I need, which is really the same tone, just a little brighter? The thinking is maybe running a 3PDT if space allows to be able to engage the parallel resistor to load the volume pot down to around 250K to get the stock sounds, and then disengage to get 500k when I go in series mode. Since I play many different guitars, usually within the same jam session/gig, I'd prefer to not have to change amp/tone settings to get where I need to.
The higher the resistance in your pickups the less top end you are going to get.  Running 2 singles in series put the resistance very high which is why you are hearing less top end.  Using a higher value pot might help a little but it's not going to make a big difference.  I wouldn't bother with a 500k pot.  Instead jump straight to 1m.  It's still only going to have a subtle effect but might add enough to make you happy.  A better fix might be to get 6 small neodymium disk and put them on the bottom of the poles on the pickup.  That will increase that magnetic pull enough that you should hear a pretty big boost in your top end however, it could cause you to be too bright when you are not in series.  There is a reason running singles in series is a somewhat uncommon mod.
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I think I'm just gonna run the middle SC101 in the neck and roll with a humbucker (probably out of a PRS SE245) in the bridge, but mod it with rod magnets in the slug coil, reverse polarity, 4-conductor wiring, and better shielding. That way I can get true humbucker tones, as well as Strat and Tele tones from the same guitar.

Having alnico slugs in both coils instead of iron poles and a bar magnet has been suggested as way to get more SC-like tones out of a humbucker a few times. However, if you just put Alnicos in one half, you will still presumably have the bar magnet in the bottom, so there is still a magnetic link between the two coils, as in splitting a standard humbucker. IOW, I don't think you suggestion is going to have much advantage, if any, over leaving the pickup as-is. I will be interested to know how it goes, if you try it.
Tony Done The alnico slugs would increase magnetic pull in the coil they are in so it would make the pickup a bit brighter and boost output  in that coil slightly.  You would get tone that is somewhere between a humbucker and single coil but it would be closer to the humbucker end of the spectrum than the single coil when running in humbucker mode.  In split coil mode, assuming the TS is running the slug coil the pickup, still won't sound like a traditional single because the shape of the coil is different but it would still sound more like a traditional single than simply splitting the coils in a humbucker with steel slugs.
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Last edited by CorduroyEW at May 10, 2017,
I've done this bit in a couple other guitars I've owned, and while it doesn't quite yield a true single-coil tone while split, it's closer to a single-coil tone than running 2 Strat single in series is to a humbucker tone. Run as a humbucker there's a sharper attack, and slightly more output, but it still sounds like a humbucker. In some ways it was easier to play heavier stuff on my PRS SEs AFTER I put the rod magnets in.

I may try to find an overwound A2 humbucker (since they're not as strong as A5) and then run A5 rods in the slug coil. Was interested in the Tonerider Rocksong bridge pickup for this reason, that and the price. It is hard finding a medium-output pickup though. In most cases most companies seem to go straight from low-wind PAF to high-output distortion monsters.