Hopefully my funds will allow me to replace my shorties with longtubes here in the next week or so. Although there are some questions that have arisen. Do my cats have to be bolted directly after the headers (pretty much attached to them, see thunderracing.com and look at the FLP and Dynatach headers and see what I mean, the cats are bolted directly after the headers. Also under the FLP headers it says that O2 sims and O2 extensions are sold seperately, why is this, Do I have to change some wires or something, please enlighten me.). Or can the cats be a few inches after the header ends? Will I need longer wires to attach my stock O2 sims? BTW what gains can I see over my shorties?

 

YU will with any longtube header cut 1 inch from cat then weld the flanges on cat and header, then bolt up.My azsm lt mounted up no sims headers came with o2 bungs installed for the two front o2 sensors,back 2 o2 sensors were unchanged.yu will however with a 99 need the egr mod on the header.

 

Please explain what the EGR mod is. Is it where I block off the EGR tube? Doesn't that set off SES codes and cause more problems?