They are being built like the single tip...meaning they will use a full 3" intermediate pipe(with flex section) and no tapers for donut gaskets, which does mean you need to mate it to a full 3" downpipe e.g. MadDad(TM) Metal V2 one-piece(or two piece with the flat flanged secondary section), MadDad(TM) Essentials Catless Bellmouth(still available while supplies last at $175), Helix, Invidia and a few others. If you do want a dual tip Whisper to mate to a Cobb DP or others that might use the donut gasket you can special order your Whisper with a 3" intermediate pipe without the flex section and with a flange design to mate with the 2.5" donut gasket.
The first production run is $649.95, which would be the local pick up price + MA. tax of course.
boostfed - the wagon it was installed on was running a VF34 turbo and a MadDad Metal two-piece catted downpipe with a 3" flat flange..however you can special order a Whisper with an intermediate pipe that will fit your particular downpipe, even stock.