Genesis
Top Post Dawg
My 2 cents on the 5th gear swap is that it's not worth it. The difference in NVH will be somewhat material, but the change in fuel economy, while real, won't be sufficient to pay for the parts and time investment for an extremely long time, if ever. At very high speeds nearly all of the fuel economy impact is from aerodynamics, which of course changing a gear ratio doesn't alter.
I don't find the existing 5th gear ratio inappropriate for 80mph sustained highway speeds, which is as fast as you can travel nearly everywhere legally in the United States. I decided a long time ago to leave it alone as there is some risk of fretting-based failure of the replacement gear associated with this change as well.
These engines have no problem running at higher RPMs and in fact NOT being driven like you stole it tends to cause problems over time (mostly due to gunking up the turbo actuator if it is not regularly exercised.)
I don't find the existing 5th gear ratio inappropriate for 80mph sustained highway speeds, which is as fast as you can travel nearly everywhere legally in the United States. I decided a long time ago to leave it alone as there is some risk of fretting-based failure of the replacement gear associated with this change as well.
These engines have no problem running at higher RPMs and in fact NOT being driven like you stole it tends to cause problems over time (mostly due to gunking up the turbo actuator if it is not regularly exercised.)