The more magnets, the better the resolution, at least early in the run, you will have with the driveshaft RPM. It's more beneficial on a fast, stick shift car (Pro Stock or Pro Mod or the like) because we are really looking hard at those early numbers to diagnose shake, ET, etc. It can't hurt on a slower ET type car, but I don't think you will see much of a difference. If you have some type of traction control or timing control that uses DS, like a Davis or an MSD grid setup, then you have to have 8 magnets, and the control unit and the Racepak can then share the collar.

Whichever you decide to get you just have to make sure you go into the config file and select the amount of magnets so that the graph will display the correct amount.

On a regular bracket car it just comes down to how much you want to spend. The 2 magnet is cheaper than the 8. But, you can never have too much data.....