I got the F1 Spec Type 5 (I think, hard to tell from the website -
http://f1spec.com/enlarge.html?http://ep.yimg.com/ca/I/yhst-76493336636070_2141_901827) and the Buddy Club rails /and/ the low riser brackets (not included - costs extra).
Installing the seats is a PITA. I wanted my seat to touch the floor and the low riser brackets allow that. However, the side of the seat slightly presses against the slider mechanism and caused the seat to slide back during full acceleration (which sucks). So, I had to raise the seat one notch in the rear to get it not too touch. Now there is a ~1inch gap. I may be able to add a washer or two under the rear bracket to make it just fit.
On a side note, I can barely use the seats comfortably as my legs can barely fully press the pedals. I have a 30" inseam so I made a ~2" thick pad to go under the current backrest to get it just right.
On the left, the low riser brackets which get the seat a lot closer to the floor, thereby giving you more headroom. On the right is the bracket that comes with the Buddy Club rails.
On the drivers seat I used the normal bracket for the fronts and the low riser bracket in the rear. The rear bracket is set in the middle. If I set it to the bottom, the seat scrapes against the tabs for the slider mechanism.
The passenger seat is set at a different height than the drivers. It has front and rear buddy club brackets. Front is set at the second from the top and the rear is set at the lowest. The passenger seat is slid all the way backward.
The drivers seat is slid all the forward.