Just because you have views, doesn't mean that those people know. So... do you want a crap answer? Also... the standing rule is... give it 24 hrs. Having an attitude after only a few hours will get you ignored.


Anyway...

As Dave said... it shouldn't be locked in at both sides. The outer shell is supposed to be ( relatively ) cool because air flows down between the pipes, so the expansion is different. Most of the pipes I've played with aren't welded at all. (inner and outer) They are held separately in the model. The inner pipe is held close to the engine, and it grows rear-ward... and the outer is held at the rear, and allowed to float on the inner piper. The outer pipe should be a little longer in the back, in comparison to the inner pipe, and that will create the venturi to draw air between.