Ok, if you are thinking about Cams and all motor you probably want at least a 2.5" system

DC JDM 4-1 has a 2.5" collector
Hytech, and SMSP also have 2.5" collectors but they are very expensive. The upside is they have incredible gains.

A 2.5" carsound cat.

For 2.5" exhaust, again Hytech makes incredible custom exhausts.
I beleave Tenabe racing medallion, Apex N1, are 2.5" exhausts as well.