Youre asking if an ITR header will bolt up to an 00-01 GSR?
The answer is yes. 97-01 ITR...all years will fit an 00-01 GSR.
I would take a JDM ITR header over a USDM DC 4-1, but a USDM DC4-1 over a USDM OEM ITR header. JDM DC 4-1 over all of the above.
Make sense?