617 engine exhaust restriction

Car is a 1983 300D turbo...
In replacing my flex pipe, the flanges were about 1.5 inches apart, so I had to make my own intermediate setup...
My question is, Would a 2 inch long length of pipe that is 1/8th inch (2 1/8
diameter vs the rest that is 2.25" diam)smaller than the rest of the system cause any sort of noticable restriction or backpressure, that I should be worried about it or get the area welded with a larger diameter pipe so that there is no restriction?
As I understand it, a diesel is just a big pump, and the only way to make more power is to burn more fuel. Gas engines have to worry about restrictions because any way to allow more air in and out will allow more fuel (because the ratio needs to be pretty exact, unlike a diesel), and thus more power. Since diesels have such an excess of air, and the fuel isnt changed by the amount of air going in, does it matter as much or at all?
Thanks very much for your help.
JMH
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Your 2.125" pipe imposes a 5.5% restriction, not material in normal driving, IMHO.
However, a badly restricted exhaust imposes a burden on any engine - to expel the burned gasses from the cylinders on the exhaust stroke.
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