Manifold Gasket Question.

[daviesbike]

i would not bother with paste to be honest, the joints that ainarssems mentioned are expantion joints when fitted together and tightened up when the system gets hot it expands and creates a perfect seal and if you put any compound on there it might make the joint not seat correctly and might not seal when hot

just my 2 pence worth

[ainarssems]

If I go for lots of paste and leave the downpipe dangling or waggling around, some paste will no doubt drop down onto the cats.

It's not just about bits of paste falling in. The stuff that evaporates from paste can contaminate lambda and catalyst surfaces reducing efficiency or stop working altogether if using wrong paste. I avoid using any paste before or shortly after cats. I know any silicone sealant and coolant getting in exhaust will do that. Some exhaust pastes are OK to use but I avoid them just in case.

[richyb66]

New cats arrived this morning. The sealing face is indeed conical so if I can clean up the face on the manifold, I'll just bolt it together dry.

Lambda sensors for the downpipes were ordered today once I'd confirmed that the current ones were 4 wire. The downpipes look long (front to back) but not that high so it looks like I'll be able to get them out without having the front of the car too high off the ground.