cbk0485

I tryed to search but couldnt find any real answers.My problem is i have a jdm mugen TL exhaust and b-pipe.And i am using a oem usdm b16 header.On a 97 hatch. The distance from b-pipe to the header is smaller now and my usdm cat dont fit. Just wondering if anyone off hand happens to know what the proper length sould be. i seen people saying varying size.16.375-17.000 inches. Thanks in advance.