i have 01 gsr and i too had that issue a 4 to1 dc header, that is meant for integra, but i believe the 2000 and 2001 have the OBD 2, so there for u have a o2 sensor in the header, and one in the cat, where the previous models did not, if u are not worried about smog then just alter the header and a muffler shop they can put the nub in for u so u can screw it in, if u are then get a new header, cause u won't pass smog, under the EPA no aftermarket part with a CARB sticker can be altered.