I use the FAST dual sensor along with the upgrade on my engine dyno every day. The upgrade includes an inductive clamp and a tachometer wire pickup . The inductive pickup is kind of cheap,but the tachometer read works good. When you do the upgrade package it lets you read the the playback in 1/2 of real time which is pretty handy. I am using mine to get pretty accurate readings for doing emulsion circuit tuning right now and couldn't be happier with it.
Keith