I have the LPP longtubes attached to my factory cat back pipe

Its leaking right at the 2-bolt flange.

what is my best option to fix this?

i know they have exhaust seal crap but it turns rock hard and the rear of the exhaust moves so it will just break away......

As far as i know, that joint is a gasketless/seal-less joint.

Has anyone elses leaked there? if so, how did you fix it?

 

No idea what year yours is, but my 2002 had a gasket there.

Since I added longtube header install though, it's been long gone and was replaced by a nice bead of Permatex ULTRA COPPER RTV. It's been on there a year and a half and still doesn't leak. Put a 1/4" bead on one flange or the other, let it skin over (about 10 minutes), and bolt it together...done.

I've actually used the ULTRA COPPER on exhaust pipe to cylinder head mating spot on Harleys several times throughout the years and it's never once not worked for me.

 

i like that idea of using rtv sealeant. alot more relaible

 

Permatex Ultra Copper is the only one that I have found that will handle the heat though...

 

Permatex good stuff. I have used it multiple times when doing headers and use ultra copper only between the header and head and have not had one come back with a leak yet.

 

yup copper rtv

 

Yup, that stuff works great, been using it for years. I actually used it right where the OP is having his leak when I first installed my Gibson catback, and it is currently on every joint in my StainlessWorks "catted" y-pipe, as well as my "cat back" which consists of the old flange off of my Gibson, a QTP 3" dump pipe, DMH electric cutout, and 18" long Magnaflow dumped over the axle...all bolted together with butt joint, lap joint, and standard band clamps. Knock on wood, no leaks. This is how I had to do it as I don't know, nor have the proper tooling to weld it all together.