Its pretty much a copy of the cosworth BDA 2ltr but much much improved for NA setups.
Micropolished crank, rods, 152.9 mm rods (136.3 mm sr20 very poor 1.585 stroke ratio vs 1.9 for the QR20) and short piston pin height, BDA style valve actuation, s2000 style ladder sump with mains, bigger bore, shorter stroke, smaller more compact thank to the lighter pressure die cast rather than sr20 sand casting process and it has so many other things going for it.
150hp base for the sentra and 170-175hp for the x-trail.
with proper exhaust, induction 15hp-20hp is freed and removing the counter balance shafts another 10-15hp hp.
without a sweat 200hp and with the right mild custom cams and ecu another 40-50hp is available even more with more aggresive cams.

To get some of these things done to any other engine will cost 3-5 times more than 1500au

http://www.freshalloy.com/site/features/tech/engines/home.shtml