Help with exhaust leak

[SandawgK5]

I have a 4" MBRP Turbo Back exhaust that I have no complaints with except for one small thing. The down pipe flange will no seal with my CAT flange. I have cleaned the CAT flange, removed the studs and use bolts, the flanges just don't mate flat. The cat delete pipe I have matches up perfect, but living in San Diego, I have to keep my CAT and would like to figure this out.

He is short video showing the gap at the flange and a small leak. Any ideas?
exhaust leak at cat flange - YouTube


Thanks

Dik

[new2deisel]

Dump the gasket and just use RTV high temp gasket maker. I used to have the same problem

[SandawgK5]

What did you use and how does it hold up? My EGTs are around 600 at hiway speed.

Dik

[new2deisel]

High temp RTV silicone. It's held up fine for a few years. Had to replace it again at the beginning of the year because I moved it. Got it from Auto Zone.

[SandawgK5]

Thanks

Dik

[WildStyle]

Ultra Copper hightemp RTV sealant.