I have an ATR one piece crossover. I got it about 2 years ago, and IT LEAKS. I tried using it back then without a header gasket and I could not get it to seal. I even tried that copper high-temp sealer stuff with no luck, so I ended up just putting my stock crossover back on.
Now I'm trying it again. I've put Felpro 1400 exhaust gaskets on. I'm hoping that this will give me a little more room/play/adjustment to make the crossover fit without leaks.
When I first tightened it all down, I went too far and broke the weld on the passenger side header where the crossover bolts on. DOH!! I had it re-welded (so much for the nice JetHot coating!).
I didn't know that ATR has gaskets for them. Why, when the stockers don't use them? And how come you need two per side? Regardless, I'll give them a call and see what they say.
-Banning.