What height from the strings do you have your P90s Phil???
I've never fiddled with the pickup heights on the SG (I've only had it 3-1/2 years, Dave, haven't got round to it yet! :lol: :roll: ) but the bridge pickup is 2.5mm and the neck is 2mm, on both bass and treble sides.
That's measuring from the strings to the middle of the polepieces, with the strings depressed at the 22nd fret. The pickups are scratchplate-mounted, so they sit parallel with the body, not with the strings, and the poles are raised slightly above the tops of the pickups.
I forgot to say before, but when I was going on about the warm fuzzy distorted P-90 sound, I meant IMO it sounds great for
lead. In fact I don't think any pickup sounds better for certain types of fat, singing leads (Leslie West again!). For chords/rhythm, P-90s work great with clean-to-crunch amp tones, but with full-on distortion I think they
are too mushy, they don't sound right. Georgia Satellites yes, Bad Co yes, AC/DC just about, in-yer-face Metal NO.
I doubt this is scientifically accurate, but it's just my perception: Humbuckers cancel hum, but they also cancel - it seems to me - certain frequencies; some of the openness, the overtones you get with single-coils. With tons of distortion, those single-coil overtones sort of bounce around and cloud the tone. So that's why humbuckers are better with distortion. Maybe. :?