Is there a secret for sealing the exhaust-to-manifold joint ? I just cannot find a way to keep the seal, well, sealed. To this end I have recently fitted a new exhaust pipe section, and have tried two different exhaust pastes to help seal the joint. I'm unsure whether the clamp is distorted (I tried taking up any clamp stretch by packing out the clamping flange-area with a 3mm wire ring as well, to no avail), or whether the two mating surfaces need a special sealing paste or washer, or if my manifold is scrap, or, or... The manifold mating surface look good and smooth(ish), the (new) pipe seems tight and immovable against the manifold. When first sealed with paste all seems well, but a few miles down the road the chuffing sound starts - I guess the paste has been doing all the work and then it gets blown out (previously left to dry overnight). Any experience of this ?