Kiichi... I guess that's the dilemma then.. Once you start getting into higher output, especially with ceramic magnets, you get more compression.
Maybe it's this particular SD in my SG standard. My brother in law owns a 2003 Dean Time Capsule, it also has a SD in the bridge, and the SD in the Dean is considerably spankier, and more articulate than in my guitar. I could always sell my Gretsch to finance a Dean Z, but I really wish Gibson made a thicker, maple capped version of the SG, with the smaller tear drop pickguard.
Gibson did some weird pickup cavity routing on the SG standards that don't make sense to me. Take a look:
http://postimg.org/image/hu43mvbfd/
That route, interacts with the pick-guard believe it or not, and it makes this kind of hollow CLOCK sound. This doesn't happen on the SG 61' models, because there only enough wood removed for the pickups. I've found the 61's have a tighter spankier sound, but yet their neck joints aren't as solid as the standards.
I think Gibson should redesign this guitar, and glue the neck into the middle of the guitar, or even through like on the Firebirds. I just find that Dean has exceptional quality, and their neck joints are something to be admired. Fantastic consistency, and with Gibson, it seems these issues are overlooked, and their neck angles seem to be a suggestion rather than a consistent standard. Of course, all these things affect the tone, midrange response etc.
Before driving yourself crazy over pickups there are a number of things worth trying to get the best out of the SG - even with the same pickup it has in it.
I suspect thart the reason the Dean sounds better or spankier is because everything counts, - like the the wood, the hardware, the routing and the way it's put together
Little things may add 5% here or there but add a few of those things together and it adds up to a lot.
You might try the following (please disregard if already different to what I'm saying.)
Basically making sure you are getting the most acoustically from the guitar and then optimising the elecs
1) try having an Earvana shelf nut fitted - amazingly as well as making chords sounds so much more in tune - there is a big effect on the clarity of the chord sounds.
2) Fit an aluminium tailpiece in place of the zinc one fitted - will liven up the high end again
3) Try Tonepro locking bridge and definitely try the locking tailpiece studs in conjunction with the aluminium tailpiece suggested in number 2
4) Try swapping the pots that are likely to be 300k ohm pots to some 500k or the BKP/CTS 550k pots, and have it wired in 50s wiring while you are at it - lots of extra punch to your tone.
5) finally - in for a penny /in for a pound - consider swapping the ceramic disc caps to something better - maybe the Jensen caps (it'll be tight but it can all fit in an SG
See what you think of the sound with the existing pickup after doing that and you may find it surpasses your friend's Dean.
One of the troubles with DC readings is that it doesn't tell the whole story
A mule might seem as loud as a Painkiller , even though wire type, magnet and DC readings will all differ.
The PK technically may have a greater millivolts but you may feel the Mule keeps pace sonically.
The frequency emphasis will be different and the perceived compression too.