Best headers for stock vtir

[TGW92]

so all after market JDM headers and cats are the same as JDM ITR headers and cats in terms of length and sizes?

yes if headers are made to jdm specifications (eg toda) then they will be the same as jdm itr headers (NOT audm)

as for cats, jdm = 12" long, audm = 18" long as well as the aforementioned differences in width.....