sauer420

I’ve tried getting my Z inspected at two different shops and although I pass all the computer tests, I fail visually for lack of cats. One of the inspection stations actually claimed I have long tube headers, which I do not. I have read information and watched a video for installing HFC, but I have a few questions about switching back if anyone can please help. My relevant setup is HR engine with Nismo intake, ART Pipes, and Motordyne XYZ pipe, all of which was professionally installed.

1) When installing the factory cats, can I use the same nuts and bolts that are currently holding in the ART pipes? They have only been on there since May, so I assume the hardware is not all rusted and difficult.

2) Does a Nismo Y pipe (the pipe used when I had the factory cats) have the same inlet diameter as the XYZ pipe? I.e. will the factory cats slide onto the Motordyne XYZ w/o fitment issues?

3) Do I use all the same gaskets for the factory cats that are currently being used for the ART pipes?

4) Should I replace any gaskets or other hardware when I put the ART pipes back on?

5) Do I need any grease or sealant when reinstalling the ART pipes?

6) Will I need to remove the intake every time I switch the pipes, or since they have already been loosened recently will it be easier to complete from underneath the car? Unfortunately NH has annual inspections, so this is going to be a regular thing for the next couple of years.

Thank you in advance for any answers you can provide!

bealljk

iTrader: (13)

Youre WAY over thinking it...just unbolt your test pipes and swap in your OEM cats...they 'should' (and I say that because I don't know your exact setup) be a near direct swap. Use the same hardware and gaskets as long as theyre in good shape and/or unless your cats have OEM studs in place. You can replace gaskets and/or hardware if they are in bad shape. You wont need to add any sealant or grease just make sure the hardware is tight on the gaskets so you don't have any exhaust leaks. You should take off the intakes to gain better access to the inlet-side of the cats. Inlet and outlet diameters should be close enough, the better question to ask is if the flange size/bolt pattern are the same - which they should be

If you have a buddy that can give you a hand it'll help to have someone working in the engine bay and someone under the car.

sauer420

Good to hear! Thanks!