i have flowtech longtubes, that i will be installing soon with my motor, and they have the slip joint on the driver side header, i know there are a few guys here with flowtechs, and other brands with slip joints, what did you use to get it to seal good?
I'd say the best seal would be a clamp for the larger tube that the primary slips into, along with some high temp sealant. There are lap joint clamps that clamp both size tubes at the joint, but I don't believe there are small diameter ones for primaries. Something like this