"Overbending"

Listen to some of the blues and blues oriented players who use overblows, like Adam Gussow and Jason Ricci. They're not trying to sonud like the traditional Chicago style, though they are influenced by it.

Overblows can sound good if you do them well (and very bad if you don't!) It's true that they supply notes in theblues scale that you can't get any other way. But most traditional blues players have found ways to work without those notes.

The firfst known overblow was in a blues tune, called mean Low Blues, byt Blues Birdhead in the late 1920s. It sounds perfectly natural and right for the tune. On the Muddy Waters record "After the Rain" (made about 1968) Paul Oscher says he used some overblows. So overblowing is not unknown in Chicago blues, but it is still unusual.

It depends on the harp. The more airtight the better. And any harp can be better for overblowing after some adjustment. Good harps stragith out of the box with no modification include Marine Band Deluxe or Crossover, Special 20, Golden Melody, Suzuki Manji and Fabulous, Seydel 1847, and probably many others.

Not so good are traditional Marine Band (not airtight enough unless you get lucky), Lee Oskars (they need work so they don't squeal) and most Chinese harps.