My 13b engine is ready to run....I ordered a VAM muffler, but since it has
not yet happened, I was wondering if I could get away with using the stock
cast iron manifold with a straight pipe attached to it, which would exit
through the bottom of the cowling. I should mention that this is on a
pusher. George Graham told me that he was using a straight, (or slightly
bent) pipe, and possibly Perry Mick is or was using the stock cast iron
manifold?  My thinking is that although it is heavy, it might possibly
absorb a lot of the initial heat as it is exiting the exhaust ports, acting
like a heat collector, and I might not need expensive inconel or 321
stainless after the exhaust goes through the stock manifold first?  Would
the cast iron manifold absorb much of the heat and possibly muffle some of
the noise as it is bounced around inside of the stock manifold?  I'm
probably grasping at straws, but with all the knowledge and experience in
this group, I figure it wouldn't hurt to ask.  Thanks to all for your
opinions and advice.  Paul Conner, 13b powered SQ2000