518 swap

You didn't say what power level you are at, but if you are NA, and If you are currently running the 2.45/1.45/1.00 ratios, a swap to the A-500 which IIRC can be had with the 2.74/1.54/1.00 gearset, then I bet you go faster! I seem to remember just a swap from 727 to 904 is worth a tenth or two. The gear ratio swap might subtract a tad more.The extra pounds of the O/D, hardly counts.
Enjoy the new freedom,don't look back.