The B6 964t intercooler is a bad copy of the real thing, if you look at a porsche 964t cooler and the B6 unit the cores are quite different, i'm not saying the B6 one doesn't work, but i will say it won't be a patch on the real thing. Taking this into consideration is it really worth loosing your rear wiper for? The AC in these cars is crap but you have to ditch this too to get it to fit.
The B&B, Kokeln, Andial style intercoolers are proven to work, and have the benifit of retaining the rear wiper and AC.
However, I would prefer to have a thinner core with a larger surface area. The real 964t cooler is about as good as you can get up to about 500bhp, but they are rare and as i've mentioned they do require the loss of your rear wiper and aircon, it's a fair trade though for the performance it gives.
I'm quite taken with the GSF cooler, it's large, thin, and very cheap. A friend has a custom made intercooler that is in a similar style to this and it is handling over 600(real)bhp. His is a little bigger and it may have better cores but it's on the same principle as far as design goes. If i was in the market for a new cooler for a 930 and i couldn't find a genuine 964t one i would be buying this. I'm not sure if you retain the wiper with this cooler, or the aircon, you'd have to ask. But, i would bet that this is better than the B6 offering