b20 r has slightly more weight but not by much the block isnt the same as the b16a/b and like the b17a and b18a/b/c it has a higher deck height similar to the b16b and the TYPIE i believe it 89 mm x 84 mm to achieve that stock in a b20 yet to do so would require sleeving the smaller b series motors tho the b20 has to be drilled for the oil lines and i reccommend new bearings and seals along with knifing and balancing the crank while your at it...thing is you get the cubes for less that all the shit needed to get a smaller b there...i say you run pr3 oversized pistons stock bottom end and stock top end R to 9000 k i say 200 whp and 150 ish wtq is achievable easy but to make that power useful run a nice JDM TYPE R LSD TRANNY WITH a nice 4.785 final drive