So my my cat seems to be going out.. Or atleast I think it's pre-cat rattle. Getting worse performance, mileage is terrible (avg 19L/100km), occasionally smell fumes etc.. and there's this clackclack sound near the back of the engine bay. The clacking/ticking reverberates around so its hard to pin point exactly, sounds like its around the exhaust manifold. Maybe a gasket leak? I only really hear it on startup and when I accelerate around low rpms 1.3k-2.7kish. I don't hear it when I'm idling. Some dude on another forum described this issue the same and they were made aware that it might not necessarily be a broken bit inside, but could be like the same effect as how a whistle works that can cause this sound.

(Ignore the heatshield rattle you hear has already been solved. But listen for the louder clacking sound)
[youtube]https://youtu.be/8JTiWyiq5qk[/youtube]

But anyways, that isn't my primary question - just explaining it in case some else might have the same issue. So, I can't seem to find information about compatibility anywhere and don't have many options for test pipes here in Canada unless I'm spending an arm.

I dont think they will fit, the placement of the engine in the body is different in a 350z and G35 compared to the M's.

Any decent exhaust shop should be able to easily put a test pipe in. The only thing would be if you want it to unbolt (instead of being welded) they will have to scavenge your old flanges from the cat coming off. You can always scavenge them 2-3 times if you put a universal cat in place or whatever, or look around on car store websites or maybe amazon and buy some aftermarket 3 bolt flanges yourself of the right size so you dont have to cut your existing ones off the old cat.

Ahh ok, thank you. Man its so hard to find any information about test pipes and such for the m35x- been scouring the planet frr. Get that its not much of a build car, especially being awd. I'll definitely buy some flanges. Had a similar problem with my exhaust. They just welded it lol. Will def save money by getting replacements ahead of time, plus in case I want to add a cat back at some point- that'd be a good call.