I definitely meant only the four stroke flange at the midpipe to silencer connection. The header flange, no way. I think the temps between a two stroke pipe flange and a four stroke silencer flange are probably within 100 degrees of one another. The silicone tape has a 500*F rating which is similar to ultra copper, but the tape has a bit more strength. It has a tendency to unravel or snap on the last winding. I still have to perform a post mortem on a recent failure on the two stroke however due to some mud puddles and hard running. It ran good for a few weeks, and it was my first attempt so it is probably something obvious. It's nice to be able to wrap it up and go without waiting two days for the ultra copper to dry.