Why b16a pistons vs b18c5 pistons?

Just curiouse after reading lots of peoples setup why many choose to go with the b16 pistons versus itr pistons? You would get more compression out of these right therefor more power? Or am I missing something? Maybe I’m reading it wrong and it’s ctr pistons that people are getting? If someone could clear this up for me I would greatly appreciate it. Thanks.

Quick question too, hondata systems only work with ODB I and ODB II, me being a non-ODB would be outa luck right? (unless I did some other stuff to be ODB I?)

In order of shorter dome to taller dome:

P73 (itr) -> P30 (2nd gen b16a) -> PCT (ctr)