I know this is an older thread, but maybe someone can answer my question.

I'm getting the p0430 with my invidia and confirmed the leak at the heat flange with the soapy water and air test.

At this point, would flipping the used mid pipe and header gaskets work? Or would I need new ones?

alternatively, if I was to place some exhaust sealant over the gasket would that do the trick? Something like this:
Permatex 80335 Muffler and Tailpipe Sealer, 3 oz. https://a.co/d/cdwxB2M

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Just order new gaskets and replace them.

 

I ordered all the new gaskets now and the copper RTV. I can't thank you enough for putting this thread together. Been battling this CEL for months now!

 

Updated to add a consolidated parts section. Included Lexus part numbers for hardware (bolts and lock nuts).

 

bump, because I still get asked about this as others start modding their cars.

 

I'm also getting codes for my invidia exhaust. I came across this and was wondering if it would work? I also have the 3' grimmspeed and round seal gasket on hand. Was just curious. It's 2.5 inch on header side and 3 inch on exhaust.

Or this?

https://www.importimageracing.com/products/077046-grimmspeed-catback-adapter-stock-dp-to-aftermarket-3-in-br-subaru-wrx-sti-legacy-gt-forester-xt

 

I looked into those and the issue is that they are designed for a different gasket on the factory manifold side. I guess Subaru uses a donut gasket at the header (this gasket is similar to the one used on the axle back section). Basically I like the concept, but I don't think they'll help us out here. If you come across something similar that adapts 2.5" to 3" but expects a flat gasket on both sides, let me know.

Tried and true method seems to be RTV with the multi-layer gasket and CAREFULLY keeping the gasket centered when tightening up hardware.

 

I am about to pick up a used invidia for a pretty good price but it does not come with any hardware. I was wondering if anyone knows what size the donut gasket for the midpipe to muffler would be?

 

I might be interested in buying your stock system depending on the year.
Ad far as adaptors randbrus sent some pictures. Make sure you use high temp orange silicon sealant (permatex high temp sealant rtv).

 

Once you get the exhaust, can you take some measurements so we can verify what size donut gasket is used? I'll update the first post once we have that info. I still have the stock mid-pipe in my garage, so I'd like to compare dimensions.

Invidia lists the pipe dimensions as 70mm (roughly 2.75") but given the mis-match of flanges on the exhaust already, there's no telling what they did at the axle-back connection without taking some actual measurements.

The other issue you're going to run into if they didn't save ANY hardware is that those rear bolts are a fixed length with a spring to hold the flange together. I know those aren't the same size as stock, and I'm not even sure of the proper term for that style to even look them up. They look like this:



The mid-pipe bolts are standard M10x1.25 x 40mm bolts and locking style nuts. The header/manifold connection up front reuses the OEM hardware.

 

If you can take some pictures, and with a measuring tool across the stock exhaust flange and the invidia replacement exhaust flange, that would help with an idea I have.
Thnx
DR4.

 

@dagored I have a 2016 but my stock system has the resonators cut out. I still have them in my garage. If you still want them, lmk. Unfortunately I don’t have any pictures of the mid pipe to muffler flange but the donut gasket has a 65mm inside diameter for the Invidia. I ended up putting it on yesterday. I could take a picture of the stock exhaust flange if you need but the inside diameter of the stock donut is 55mm.

 

@LoSt180 I ended up buying a digital caliper and measured it. The inside diameter is 65mm for the donut gasket. I got one off amazon and it fit pretty snug. I ended up watching a bunch of YouTube videos and was able to put together a list of all the hardware. A lot of pausing and zooming in.
I ended up with
8 M10 x40 mm Bolt with nuts(replaced the ones up front because they were rusted)
4 M10 x67 mm Exhaust spring bolt with nuts
2 65 mm Donut gasket for the muffler
In addition to what you have listed at the top of this post

 

x2 on the permatex. I am still on the original invidia hardware 2.5 years+/22k+ miles with no CEL…yet..

 

Hi allday123,
Can you send me the pictures of your stock exhaust system?
And if you can figure out a way to get a private message to me then we wouldn't have to both these fellow RC F friends with our conversation.
thanks
DR #4