True. Any tach should be on the money.

There are just too many variables when it comes to figuring actual vehicle speed by measuring trans RPMs. Even tire pressure can change it a bit.
Even an error far too small to notice at normal driving speeds will add up.
Especially when you're going over twice the speed limit!

I hope your chip arrives soon!!! You'll love it!

Matt
-I'm afraid my 150 days are over, they opened the stretch of highway I was using...-