What are you guys using? I currently have some copper gaskets but they leak. I have Hooker Fenderwell headers and 452 heads. With the Stealth Super Sniper install I want to get the exhaust leaks fixed prior to firing this thing up

I"ve had good luck with Jegs brand copper gaskets on my 360 and use Mr. Gasket ultra seal gaskets on my 440.

Remflex has alot of praise.
http://catalog.remflex.com/

I ordered Remflex and Cometics for the head side and Remflex for the collector side.

I currently have copper gaskets and they are a joke, not sure the brand though

i have a cometic type , as recommended with the Trickflow heads . Use a little skim orange exhaust silicon been ablle to reuse them several times . Best i have had

Tex

if --- the heads and headers are true and flat ,
a little permatex red and never a leak here ...

I have used them 2x.. not cheap but they work

How thick are the header flanges? Especially with long fenderwell headers

A thin smear of copper rtv on your copper gaskets and you should be good. Wire brush it off and apply new rtv if you need to take it apart.

Those copper gaskets don't crush at all from my experience. The ones I tried were hard as hell so they are either touching or not touching and not touching is leaking.

Remflex

This is what I'm experiencing too, I figured they'd be a softer copper to allow for them to crush.

Pretty thick, they are 20 year old Hooker Super Comps I'd say 3/8" without going and measuring them

FelPro has been good for me with aluminum heads.

I've used them and have been happy with them.

Never had any luck w/ the copper or aluminum header gaskets.
Just high temp silicone works good if you can easily apply it and pull the header straight onto the mating surface. On most big block stock body cars, you can't really do that.
The tan colored Indy gaskets work real well, but they're for the big port heads.
I've had good luck w/ the Fel-Pro gaskets and I have a set of Remflex gaskets on the way. Figured I'd give them a try since I've heard good things about them.

I agree with just a (thin smear) of silicone if we're talking a manifold or header with a machined flat flange.

I think Hooker has a ground down but -raised- weld bead at each port so not sure if that's flat enough or enough surface area.

I think the issue many times is not the gasket, but the header flange. I personally have had the best luck with the aluminum layer type gasket for sealing and reuse. Hi-temp RTV works if you don't mind it squishing out and looking bad.
But headers with a raised welded ridge on the flange are just junk. I have built the last few sets on my projects, I weld in stubs, and then put them in a mill and flatten them just like an OEM exhaust manifold, then build and attach the tubes. I have had no leaks with any type of gasket.

If the flange is machined flat just a thin smear of rtv works. So thin it's not squishing out everywhere. I prefer Toyota black FIPG.

no matter the header brand or gasket used, separate the end tubes from the center tubes [a hacksaw works] and drill one hole on each tube mating flange oversize.
this allows for flexing due to heat, and ensures no leaks.
this even works to seal cheapo brands with thin flanges.
i stole this trick from mr. Pbody years ago.