Quick pup questions

[JJLipton]

Sorry if this has been asked before, but what makes the fender mustang pickups so special? Are they just flat pole pieced strat pickups or is there a special design that goes into their production? I've noticed the mustang sounds alot like my strat sometimes, but with less attack and more sound options. But as ive noticed with a mustang i owned in the past, there is a drastic volume change from switching from clean to distortion and i'm assuming that is why many players change pickups to preserve that mustang sound while avoiding the volume changes. Also, can lace sensor pickups be put in and out of phase? I forgot i had two golds lying around after trying them out in my jaguar and being disappointed.

[Will]

Vintage mustang pups are flat pole piece and use a slightly larger magnet slug then strat pups, but the same DC resistance. The plastic cover has an insignificant effect on the sound. The biggest issue with the mustang pups is the low output, even though the pickups are more powerful then strat pickups from the same era.

In a strat, the lowest output pup (bridge) is also not routed through a tone control, making it louder. THe strat also has a longer scale (more string tension) and brighter body wood, which gives more perceived volume due to the increase in treble. The mustang sounds darker and seems quieter, though the output is about the same. People (like me) usually put higher output pups in the mustang to compensate for the darker sound the guitar naturally has.
Lace sensors can be put out of phase - I figured that out when trying to wire them into my strat.