I dont know if anyone has any experience with this but can a car loose whp on a dyno by switching a final drive lets say from a 4.40 to a 4.785 (gsr tranny) providing nothing else changes? There was a guy at a shop that I was at yesterday talking about this and I was curious. The shop owner also said its usually a 10 whp difference or so (less).

 

There was actually just a thread on this in here a couple weeks ago. You may want to search for it.

It will depend on the dyno being used, but it can have an effect on the final number. Yes.