I'm trying to figure out how these go on. Do the replace the piece with the exhaust arches or simply get stuck on over that piece?

I put on a fast intentions exhaust a couple weeks ago and now have an open space where the stock muffler was that just doesn't look right. From the back you can see open space and actually see the RAS rack and motor.

I need something to fill the space.

My concern with a diffuser is tip clearance if it simply lays over the stock piece. The tips on the FI exhaust don't line up perfectly with the existing cut outs. They are about a 1/2" too wide on either side so they are not centered in the arches. They are pushed to the outsides so the clearance between the tips and the arches is only about 1/4" on the outside curves.

If a diffuser just overlays the stock cutouts I'm pretty sure the tips will touch on the sides.

Can anyone school me on how these mount?

 

+1 id like to know this also... and if someone could tell me whats the difference between brands out there? ive thought about buying the one klumzyee sells but noticed that theres the kakumei one on ebay for much cheaper... anyone have experience with these?

 

it mounts over the stock piece....you can make most exhausts fit by simply adjusting the hangers....as far as differences, i went with RAVSPEC because i wanted carbon fiber, they also make a FG version...i'ver heard that the authentic nismo fits like crap so i'd avoid it

 

It goes over, I just installed mine not to long ago, my exhaust rubbed, not on the side but on the top so I made a DIY solution:
https://g35driver.com/forums/body-in...-solution.html

 

You'll have to be more specific as there is more then one rear diffuser now available.

There is the nismo rear "diffuser", which really isn't a diffuser at all. It's just a rear lip add-on or overlay.

Mastergrade just released their "TS" style rear diffuser which is a replica of the Top Secret 350z rear diffuser. This is more of a functional diffuser as it helps increse laminar flow.

 

aw crap that's what I was afraid of.

Good info on the hanger adjustments for height. Unfortunately that won't help me on the width. There is a rod welded between the 2 pipes just before they bolt to the mufflers that looks like it needs to be shortened and rewelded to pull the pipes closer together. I was under there for an hour loosening and retightening every connection and no matter what when everything is torqued down the tips go wide.