Mid 2020, started to have some Cat issues(small crack), which I think was related to some other repairs. A year later that crack got worst and CEL popped up every few 100s of miles (P2A00). Spring of 2021 had to cut the resonator in order to weld new Y pipe. End of spring, decided to order a new set of FI Cats( old ones lasted 5yrs). 600+miles later and no CEL after the new install.

Stock Y pipe🗑

Resonator removed from Cats

Custom Y pipe

New FI arrived (end of August)

Installed

Zoomed in shot of the flange

Finale

 

how are those resonated HFCs? Do the resonators affect the power in any way?

 

Do you think the cracks in the welds had anything to do with the FI design consideration that you do away with the support brace under the transmission?

That always seemed odd to me, although I've some faith that FI knows what they're doing, and in the last 10 years here this is only the second time I've read where someone's FI cat welds cracked.

 

^^ I've never liked how they got rid of the cat bracing. The exhaust already doesn't have enough hangars really and then they removed the connection point to the transmission. I went with the Z1 for that reason.

 

I don't think so, I had the resonator removed for a few months and I didn't notice any power loss nor sound.

 

I'm not sure who to blame, especially since mine were welded directly to the flex pipe after a few years and I believe the entire pipe was moved to do some repairs. A muffler shop guy, blames it on the weld design and possibly due to the way the engine shifts. IDK.

 

Interesting, didn't know that about the Z1s. I still have my original cat bracing. Wonder if it can be modified to fit with the FIs.

 

yep.

https://www.myg37.com/forums/g37-sed...intentions-hfc

 

I was thinking you did this right. Link didn't work, but I googled it and found it.

 

Sorry. Here: https://www.myg37.com/forums/g37-sed...tions-hfc.html