I use a 60mm on my B16A CRX. Perfect size IMO.

I wouldn't use a 2" on a B16A though. On a D16 sure, but B16 I'd go 2.25" up to 60mm.

B18C 60mm-63mm.

K-series has long been proven to make more power with the 3" than a 2.5-2.75".