I love the IS500! It's comfy and compliant when I want, and rowdy when I'm feeling it! It's not quite as aggressive as an RC F but that's ok with me. Thank you for clarifying what happened. Even though the Ark might not have this problem since their pipe is 2.5," its astounding how complex the issue is for those with the Invidia exhaust. Just so I'm 100% clear, only 1/16" of the OEM crush gasket is actually being sandwiched between the 2 flanges? Like this (not to scale):



This would make sense that it gets all burnt up within 24 hours because the backside is completely exposed to exhaust gases. Yeah it's hard to imagine essentially a 1/16" wide gasket creating a solid 100% seal, but at least now I understand. Sorry for hi-jacking the thread. I hope my diagram makes up for it haha!

 

Yup, that's pretty much a perfect diagram of why it's nearly impossible to get a proper seal using the OEM crush gasket. You would have to hold the Invidia pipe nearly perfectly center and have zero shift while tightening to have a chance at getting a seal.

Then if you look at this joint sideways, there's a void on the header side. So if you tried using a flat gasket smaller than 3", there's noting supporting the "fire ring" - it's basically floating. With no support they blow out the rest of the gasket in short order. A 3" gasket is at least supported by the flange on the Invidia side. That's where the stacked gasket concept came from in my Tech Tip thread.

 

You're diagram is prett ymuch correct on a good day!. There jus tisn't enough material on the OEM gasket to seal it.
All Invidia is create an adaptor, like Grimm has done for the Subaru....
I have not contacted Grimm's but I'd bet they'd be willing to create an adaptor specific to the Invidia to RC F exhaust system mod.
DR4

 

Almost two years and lots of high RPMs and no CEL since using the Grimmspeed gaskets. I used the standard Grimmspeed gasket (not the 2X thick) and no sealant.

 

Blown out 2X Grimmspeed, OE crush gasket all mangled up and carbon blow out marks on pipe.

Looking at the pipe Invidia stretched the pipe to 3”… why? So dumb.

 

Sorry for more potentially stupid questions, but can exhaust leaks like these potentially foul up the downstream O2 sensor(s)? I know there's a cup to protect the sensor but not sure what it actually does. And if this O2 sensor is fouled, would that cause sluggish performance? Ark just told me today that when I came in for the re-install I actually had a leak but no CEL. I was completely unaware of this. So presumably my exhaust has been leaking for some time and I wonder if that's damaged my O2 sensor.

Related, I'm still thinking what P0420 could be and also replaying how my car felt after the CEL. The engine was idling at 500 rpm (which I've read is low but normal), and if I pressed on the gas on the freeway while at 2k RPM, as my RPM would climb to 2.2-2.5k RPM my transmission would quickly upshift and RPM would drop back down to 2k. It felt like a loss of power but maybe its normal and I was paying attention to it too hard. I had no problem getting up to 70 or 80 mph, but never tested the CEL with WOT or Sport+. If anyone has ideas on what I can do to test for actual sluggish behavior, I'm all ears. Thanks.

 

I got to thinking about how flat the flanges were. Marked them up with a Sharpie and then hit them with an orbital sander. There’s very little ‘contact patch’ and both the flange and O2 bung surfaces are uneven….right where the blowout marks are.

 

You didn't have the 3" gasket perfectly centered on the flange when tightening up the exhaust. The score marks look to me like it was just hanging on the bolts and tightened up with little to no effort to hold everything centered. Unfortunately that's a very common installation error.

 

You used both the OEM plus grimmspeed at the same time?

Looks like from the picture above the gasket wasn't center. You can see how much more the gasket imprinted on the top compared to the right side.

I did what Lost recommended from a post where he filled the void area with sealant. I did the same thing then lightly coated both sides of the gasket. Made sure everything was aligned and finger tightened then came back 90 minutes later and properly torqued the nuts'bolts to spec then waited the following day according to Permetex's instructions on letting the sealant cure.

I get not everyone can wait a day but so far most of these CEL's are coming from bad installations. Still doesn't take the fact that Invidia could easily rectify this for instance like what Joe-Z/Borla exhaust has in terms of the recessed area for the flange for an OEM crush gasket. But many people using Grimm speed gaskets and the problem either never happened or it has gone away.

-Nigel

 

I agree with Nigel re the OEM being used in conjunction with the Grimms. 3". My -F still has not thrown a CEL with the OEM and Grimms combo plus selant. Looks like that will ultimately fail. However, my guess, is the sealant is the key as it will keep the OEM in the correct position. Time will tell.
DR4.

 

Perfectly? I thoroughly read all the threads before hand. The 'error' is Invidia building a crap exhaust.

 

No, when I bought the car it only had the OEM gaskets. Upon removing them it was very clear why it was throwing codes. I see what both of you are seeing but to honest I don't know what side those marks are from. And they were centered...I made sure of it. Crap wrong flanges on Invidia's part.

Owners need to stop condoning Invidia's crap design and all the vendors who continue to sell Invidia. Profit before quality. What a concept.

 

Nonsense. How is mating a 3" flange to 2.75" flange a 'bad installation'?

 

There are several problems with the Invidia to stock exhaust manifold connection which Nigel and others have outlined in detail. Basically you are correct that Invidia shoul dmake their flanges compatable with which car they're going on. I bet all of us woul dbe willing to pay the extra cost that might add while foregoing the CEL problem. But they won't so you look for a solution.
DR4

 

Jim,

I get it, you had a bad install and the flanges aren't the best. Why they used 3" over 2.75" is anyones guess? Again, there are many people who have installed this exhaust and have zero issues after replacing the gaskets. You are in the slim percentage that unfortunately it didn't work. I've installed two of these so far. Zero issues. Lost tracks his cars which is 100% going to see more abuse than people using it on weekends. And Sunny mentioned he replaced his two years ago and has yet to see a problem or CEL come back.

Invidia isn't perfect by any means but again it's a $1,300 catback exhaust, which is pretty much the cheapest one out there for the RCF. One can accept that and realize that it's not going to be a GT Hauz/Tom's build quaility...etc. OR, pay the almost double/triple amount and get a GT Hauz/Tom's and have OEM fitment.

My gripe isn't even with the flanges it's with the exhaust hanger posts that don't have a nub on the end of them so that way it stays "locked" in to the exhaust hangers and wouldn't accidently by some off chance come OUT of the exhaust hangers. That was a more glaring issue to me wondering why they wouldn't have made the posts with the nubs...seems more saftey issue to me if the damn exhaust ends up coming out then starts dragging on the ground...

We get you don't like Invidia. You have the beauty to buy whatever exhaust you want and come back and let us know how it is in comparrison. That's the wonderful thing with forums. If there is an issue or glaring problem most come together and try and find a solution to let others know. I did research on gaskets and made the recommendation a year or so ago to use Grimmspeed gaskets and recommended them as I posted. Lost made a nice how-to to indicate for future people what issues they would have with installation. I can tell you on FB at least, the people that have gotten the exhaust, there is a significant less "I have a CEL from invidia" postings where as a year or so ago you'd find a lot.

I wouldn't say that everyone is defending Invidia, more so we realize for the $$$ amount it's not a bad bang for the buck. It's reasonably priced considering all the other options. Why other manufactures decide to add the "lexus" tax on stuff is annoying. As much as I'd LOVE to buy a Tom's titanium catback exhaust I can't see spending $10k for an exhaust that is going to yield me the same result in HP that a $1k sytem does. It will sound very similar as well... perhaps even quieter since Tom's doesn't delete the secondary cats like the Invidia does.

I wanted something that sounded good, wasn't obnoxiously loud, and most importantly did not drone. Invidia hit all those points for me. To get the same results, I would have had to buy an Apexi resonated mid pipe $1,200, and a Tom's Axle back s/s or titanium ($2,500 / $5,500).

If I start getting CEL's due to exhaust leaks then I'll take action on what's best at the time by either completely replacing the entire system or taking it to an exhaust shop and having them make or weld proper flanges on (the latter would still be significantly cheaper than replacing the entire system)

-Nigel