Flange Gasket?

[Loudmouth LS1]

I just got my Jet-Hot LT's and True Dual setup installed on my car a few days ago. I didn't want the exhaust shop to weld my header to my x-pipe, cuz I wanted the headers to be easily removed, so when I get my heads and cam done, they don't have to be cut and rewelded. So they said the best thing they could do was to weld a flange on to the headers and the x-pipe, so it could just be unbolted. Well, the headers only came with two flanges, but I had two from my 3 in cutout, so we used those and the gaskets they put in looked real flimsy like. Well now it's like 2 or 3 days later, and i'm getting a ticking from the drivers side header near the flange. I'm assuming I probably burned out the gasket already, cuz i've been gettin on it a bit, and I would like to know what the best gasket would be to use so that this doesn't happen every two days. If anyone has any info, it would be greatly appreciated, thank you very much!!