I have not been out this year so no solid info yet last year I was running right around 60mph on GPS.
I'm not monitoring AFRs, the impeller is a 12.5/18, stock ECU so 7600rpm max, 4" intake was also done, I hope to be in the mid 60s while maintaining reliability.
I'll post some impressions and speed numbers after the first ride.
You don't get any extra speed unfortunately, just power. The speed is limited by the rev limiter. With the extra power, however, you may be able to get a few extra mph by adjusting the pitch of the impeller.