ultra copper gasket maker temp rating?

[1quick6]

I want to seal up my ds header to crossover pipe, so someone suggested to me that I use ultra copper in the crossover and let it sit for a few hours before mating it to the header. My question is, the only copper sealant I can find is rated at 700 degrees. Is this ok to use or is there a better and higher rated sealant?

 

[87GNSteve]

No sealant will work when your boosting; EGTs get to 1600+ and the pipes come close to that. I made gaskets and sandwiched them in there you really need a 3rd arm then to install the crossover but so far its working.