I keep wondering if I should try for a thicker, stronger sound by having my vintage Mustang pups rewound, or by trying new ones. So I contacted Guitarfetish (thanks for the tip, Mcconn). Their pups don't quite fit the Mustang, according to Jay there. The closest they have are Strat-sized and he says Mustang pups are a little bit smaller.
Jay suggests using the Seymour Duncan pickups designed for Mustangs.
But, being new to electric guitar, I'm getting bigger sound and discovering new tones as I get better at using more of the potential in my Peavey Classic 30.
Hope this helps.