I first discovered the Ferrari 355 Spider seats on this thread on page 5 (I think). Like many of you I had been searching for seats that were comfortable and fit the car. These seats are by far the best I found. Most are too big or sit too high for a car with stock floor pans but these are a very close fit. The seatbelts are integrated into the seats so I was able to cover the holes in the rockers and ordered my bulkhead reduction kit without provisions for the rear seatbelt retractors. It makes for a clean look.
I wanted to keep the ability to slide the seats back and forth so sliders were required. The Ferrari sliders are powered and I didn't see the point so I saved some money knowing whatever I used would require modifing. Sparco double locking sliders seem to be the best option. I bought 3 sets of sliders because I needed extra material to extend them. In speaking with Dennis Quella he recommended angling the seats slightly inward towards the pedals and foot well on the passanger side to make the car more comfortable. After sitting in the seats and moving them around in the car I opted to try angling them. It's hardly noticable but it does make a difference.
Here's a look at the process:
I had to cut out the factory spacers to lower the sliders as much as possible.
I had to use flat top countersunk allen bolts to clear the sliders.