I've a bent PSS-170 at home. I really thought I'd replied already to this thread. Must have dreamt it.
Oh well, it's possible to bend it. I didnt find a pitch mod, but as mentioned already, it's possible to mess with the lines between the chips, there are about 5 of them if memory serves correctly. I've just shorted out mine to each other and ground, and it's working sweet, I'll have a go at cutting the lines and trying a little patch bay next. But even without doing that, just by shorting the pins together you get a lot of crisp high pitched bleeps, clicks and toots, and occasionally some suprisingly deep bass aswell. Although the tones are not as mindblowing and weird as say a speak and spell, they are quite stable and predictable, which makes it overall a very useful instrument. I'll take some pics of the inside this weekend when I do the trace cutting and patch bay mod. Stay tuned.