I just ordered a set of MACs midlength headers and had a couple questions. I read several similar threads but haven't getten any definite answers to these questions. I guess I don't fully understand how the MAC y pipe and cat/orp connect.

1. Do you have to cut the stock y pipe from the cat when installing new y pipe?
2. Is there any weldind needed for installation?
3. I want to get an ORP but I need to be able to put the cat back on for emissions. What EXACTLY do I have to do to accomplish and interchangable orp and cat setup?

Sorry if these seem elementary to some but I'm trying to learn. Thanks in advance everyone!

 

With thier offroad pipe it is a complete bolt on.They now offer a bolt in cat that you can switch back or forth .If you dont mind cutting and welding then yes you can swap back and forth because they will be the same lenght .When you cut your factory y-pipe and weld on thier flange it is the same length as thier offroad pipe>

 

The Y pipe is a direct bolt up with the ORP. If you get the ORP then just have your cat welded up with the correct flanges and same length as the ORP.... they'll be totally interchangeable.
One thing to consider... when I got my MAC headers for my 93, they came with an EGR flange coming from one of the primaries. 93's don't have EGR, so I had it cut off and welded up. I meant to call them and let them know, but I got them so long before I installed them that I thought they may have corrected the issue.... probably not though. I know they weren't for a later year because the air injection was correct, but maybe they got an EGR flange by accident or something.
Good luck with the install if you're doing it yourself. It took me and one of my ASE certifified buddies 12 hours to do mine..... I had a broken bolt in the head at exhuast port #7 and had to center drill it and extract it.