'00 L to GT 5MT swap, speedometer error

Just swapped a rebuilt TY754VCBDA (5MT from '01-02 GT) and 4.11 LSD rear into my '00 L wagon along with a Fidenza 110001 aluminum flywheel and Exedy 15801 clutch kit, complemented by a recently installed Kartboy short-throw shifter. I love the feel and driveability of it all, the 4.11 instead of 3.90 final drive ratio, limited slip, etc.

 

BUT!... There is a problem. My speedometer is now reading approx. 5 mph fast, and I have to rely on my GPS to know my actual speed.

 

What's the fix? A new speedo? New speedo drive gear in the tranny?

I plugged a scanner into the OBD connection, and the Vehicle Speed Sensor function shows the same speed as the car's mechanical speedometer, while my GPS indicates a slower speed.