Originally Posted by cgocifer

No worries, I wasn't directing my explanation to you, just providing info. to those who may get bogus info. from the shops and others. Again, that shop was full of it, if they were talking about aluminum. Trust me, if aluminum was a viable material for exhausts, I'm sure many race teams would be using it to save weight. Aluminum is almost 50% lighter than steel. YOU CANNOT WELD STEEL TO ALUMINUM without a transition piece or specialized filler alloys (expensive).