hey Jim, great info.
The Montgomery OS TB setup i have is:
52mm top of the Hartley stacks where they start to bell out
51mm at the TB/stacks connection
49mm at the blades
below the blades there is a tapered section, goes from 49 down to 44.8
44.8mm where they go into the head.
You think that config will work any better than stock TB/stacks with Carpenter's short intake/big exh head & 465/425 cams, 18.3-18.5:1 CR??
One of these days, i'd like to try yr new big exh head