Making sure both mating surfaces (o2 housing and down pipe flanges) are truly flat and clean are very important. I would not use anything more than a light coating (spray copper gasket) on good quality (new) gaskets to help hold them in place during install (same for o2 housing to turbine housing). Make sure all new parts are torqued to spec to ensure even torque on all fasteners. Nickle-based anti-seize is great to use on all threads to make removal easy later. Re-check torque after a few heat cycles (when cold) to make sure nothing has worked its way loose.

I have has good luck with OEM turbine-to-o2 housing metal gaskets and Vibrant gaskets for the down pipe.

I always block sand the surfaces, and I run no gasket or sealant. No leaks.

I like the multi layer gaskets when ever possible.

using oem lancer 4 layer copper for head to manifold, extreme psi 6 layer for manifold to turbo, oem single layer turbo to o2 (recently found a multi layer for that too)

I have tested this sealant with good success https://www.designengineering.com//...c/component-specific-products/gasket-solution

Watch this video:

I had the same issue, my o2 housing wasn't sitting flush. It wasn't a flat surface, so I stuck it on a belt sander until it was flat. A file can work too like Jafro does in the video.

As a quick fix I'd do copper rtv very light coat on both sides of gasket. Just me. I prefer vband EVERYTHING though.

Vband would be nice.. my honda is vband everything.

Both my o2 housing and manifold to turbo gasket are leaky now.. i can see the smoke from my leaky valve seals puff out of them at start up

I like the copper gaskets. I have one for manifold to turbo, and it's working great.

darknezz7 said:

I like the multi layer gaskets when ever possible.

using oem lancer 4 layer copper for head to manifold, extreme psi 6 layer for manifold to turbo, oem single layer turbo to o2 (recently found a multi layer for that too)

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Ive used these aswelland have had good results.