Angus, I got a set of Thunderpipes last fall and I'm not sure that RTV is necessary. I put some on mine, but most was squished back out when I fitted the pipes. There are no leaks. I just used the regular, clear Permatex brand. That far away from the exhaust port I don't believe there is any need for any high heat type. If you do use it, use it SPARINGLY, because you're going to end up wiping most of it back off anyway! P.S. - I LOVE the pipes too, they make the bike sound awesome!
