theres not too much on the rotating mass modifications.
there is some on the turbocharging and compression.
http://ecomodder.com/forum/showthrea...ild-26722.html
http://ecomodder.com/forum/showthrea...rbo-11881.html
the honda isnt a build thread but really cool.
in regards to the d15z1, im a huge fan of this engine since learning of its existence a year ago. ive learned as much as i can and continue to learn. anyhow they are born to run lean burn from the factory. the california models did not operate lean burn due to strict ca emissions. the federal models run 19-22:1 afrs from the factory. (according to my afr gauge in mine) it runs about the same compression ratio as most other d series except it has a smaller combustion chamber in the head and to account they made a dish in the pistons. they look like dished turbo pistons. the factory P07 ecu does very well with lean burn.