This new interview with Mark Raffauf mentions that IMSA has created it's own DPi already for baseline testing which I find pretty interesting.
http://www.racer.com/more/viewpoints...ll=&limitstart=
"All the P2 cars will be done as well in the same fashion on our model. The focus is DPi first, but our [DPi] car is considered to be relative to the data we have from those [four constructors] that have completed their own P2 model testing. Ours is the fifth [P2] design; you could take this car and build it and it would work. It is a totally functional 2017 P2 design."