Don't know if some problems I've had with my early 235 exhaust system
pertains since the later systems are most likely quite different. However,
here's my two cents worth, FWIW.

I bought the factory exhaust system very early on and the mounting
provisions had a tab welded to one pipe (actually, it was a large pattern
washer) that was designed to bolt to a sump bolt on the engine on the left
side, just about behind the rear intake runner. Didn't last 50 hours before
it pulled up a chunk of pipe wall in about a 1 inch vee-shaped tear. I had
the tab removed, the damage weld repaired and fabricated a ~ 0.090 thick
steel bracket that clamped to the exhaust pipe and attached to the sump bolt
sandwiched between two exhaust-joint coupler springs from a Cessna (sorry!).
The springs are about an inch long and are very stiff and meant to be used
in the temperature environment of an ehaust system. The bracket has an
oversized hole to allow it to move a bit while being restrained by the
springs. It's now worked just fine for 600 hours +, i.e., no more cracks.

As per the Lancair instructions, the aft end of the two pipes at the exit
are inserted into a single collector and pinned and are hung from the
airframe with a stout spring about 6 inches long. I actually have two
springs there for security in case one breaks. This attachment seems to work
fine as I've had no problems with it.

Dan Schaefer