The 10th gen Civic Si ("protoype") was revealed today -- scroll to 5:20 for the actual reveal:
Press Photos
TL;DW:
- 1.5L turbo
- LSD
- lighter and more rigid chassis
- adaptive steering and suspension
- optional brakes and HFP wheel package (no more machined face, black inners

)
- looks like it has different bumpers, wing, center exhaust
NOT a detuned Type R engine