Sat Nov 11, 2017 5:10 pm by Buzzman72
When the exhaust exits the manifold, it's extremely hot. The front exhaust pipe radiates a lot of that heat, and more is lost in the muffler.
Considering the diameter of tailpipes and intermediate pipes on comparably sized sixes from the same era, the 1-3/4" is probably sufficient. The 3" front pipe will decrease the velocity of the exhaust, and cause it to shed some heat. The smaller tailpipe will likely increase exhaust velocity a tad, but not cause backpressure problems.
These engines turn about 3600-3800 rpm maximum...not exactly a race engine by any means.
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