Bloody Stupid Question Time!!

[fangsport]

i have recently put a stock 2TG in the TE71 as the ol' faithful 3-T got slightly toasted when it went on fire( and no.4 bearing is getting a bit noisy), and was curious to know if the twin-cams need bigger primaries.
admittedly the flows arn't huge, but since the 2-TG went in, there seems to be a noticed restriction in the exhaust .

Any thoughts?

[crispy'86]

Hey the 2TG primary pipe size is bigger on the 2TG than 3T front section of pipe. I noticed ther is around 10mm or more difference in size , don't quote me on exact size in mm but itIS larger on 2TG front pipe than 3T

[fangsport]

same flows on both engines, both engines have run on the same pair of 40's.