You will lose syncro rev functionality. When you go to down shift the rev match will be off by a couple hundred rpm. There is no way to get around this currently. In order for the rev match to work properly a constant hard programmed value for each gear is coded somewhere in the ecu. Since your final drive changes with a 4.08 swap your overal gear reduction changes and the constant coded value in the ecu is then wrong. Is it physically possible to change? It is if someone knew how to access the info in the computer. To my knowledge no one has been able to even find it much less modify it and this is the only thing that held me back from a 4.08 swap. I was so close to pulling the trigger but theres just something about knowing that a feature on my car doesnt work correctly whether i need it or not.
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370z NISMO 0675 327 rwhp 280 rwtq - sold.
FD RX7 single turbo 508hp - sold.
Lexus IS-F 5.0L V8 
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