The best harmonicas for overblowing are made by Joe Filisko. These however are difficult to come by (checkout the Guild's website).
There is a number of other harmonica customizers that make very good overblow harmonica's.
also see: "What production harmonica is most easily modified to an overblow harp?"
what about the special SBS hohner? suzuki overdrive? xb 40 hohner? The SEYDEL 1847 ?
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