Swap into new Low Mileage NB 00, now Speedo off by 5mph? Also Tach and MS Fix?
 

Alright I got the chance to snag a 47,000 mile 2000 Miata to swap into for 300 with a lot of nice goodies so I did it. I have since put on it 1500 miles and I have found a strange issue.

I noticed going through those speed check points that my speed was off by 5-8mph. At first I thought it was just the machine but when it happened more than once I had a friend pace me in a stock vehicle and sure enough there was a 5mph difference.

Now I doubt this has anything to do with MS, I am guessing that maybe the prior owner swapping in a different dif (Maybe to gain LSD as they installed Koni Adjustables and lowering springs, the car was very clean before I installed all of my goodies as well) and now it has different gears which I am guessing means I need to corresponding VSS Sensor or could it be something else?

Also on a lesser note, even since going MS my Tach has been off slightly, is there anyway to adjust/tweak this. I did not think there was but might as well ask while I remember it.

Thanks!

Boing