I'd rather get OEM JDM goodies!

Depends what your getting, are you going to go with 60RS or 70RR?
If 60RS, I think it'd be better getting an OEM 2-1 part (never seen it pop up for sale before)
If 70RR, get the Js Racing 4-2 header. as the 2-1 piece that comes with the 70RR will be perfect. Then you just have to chop up the 2-1 part to fit a cat.