Originally Posted by
NitroOB4You
I havn't run the FM, but from what I have heard, basically, the Pre will have a more snappy bottom. The FM smooths this out and gives a little more RPM range on top. The FM ( I'm guessing? ) will probably also have slightly better fuel mileage.
What he said
the FM turns about another 5000 RPM on top compared to the pre run but it does this by taking a small amount of the bottom end. So full mod in the buggy for the big tracks and a pre run for the smaller stuff. I run the FM regardless of track size and I still think it has plenty of get up and go.