i wouldnt go any farther than port matching the exhaust if it even needs it.
there isnt much experience with M60s at all. my intake matches perfectly to the intake side of the head so I wouldnt be surprized if the exhaust port is the same or designed for the best performance.
free flowing exhaust will move the powerband up even higher but sounds cool.
You change rear gears to a 3:64 yet?
95 E34 530I V2.37
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Those who make peaceful revolution impossible will make violent revolution inevitable.
John F. Kennedy