Too be honest Felix I think that PIS can vary from car to car. It shouldn't be set just by a number for instance 4.3. I also don't believe you will get it down to 3.8 at least I've never seen that and I'm a member on the U.S. forum. If you want your car to perform the absolute dead level best with the most aggressive PIS to save on clutch wear, ask your Tech to use the Gear box RPM's to lower it.
Make sure the car has been taken out on a nice long drive. Maybe about 30-45 min. (I will tell you why in a second). Then lower your PIS to about 4.5 mm first. Check the Gear box RPM's to see if you are picking up any friction disc drag from the clutch on the flywheel. These F1 cars in neutral still hold the clutch open. It's not like a normal 3 pedal in that it releases the clutch after you switch to neutral.
If you are not getting any drag lower it to 4.4, then to 4.3 ect. Chances are with your Gran Sport you will already have fly wheel drag at 4.5 mm. If you do, open it back up by .10mm until you don't. Once you register 0 RPMs on the Gear box rpm sensor. Rev the car to 2000, check and see if it's still bumping the flywheel. If it is you can open it by one more .10mm or if you are like me to push it to the absolute closest setting I will start doing .02 or .03 etc. Finally, I will tach the car up to about 5000 briefly to see if when it spins out it touches.
These steps are important because you can glaze your friction discs by allowing you clutch to drag off the flywheel. It's why Ferrari/Maserati had recommended lowest settings. I don't necessarily agree with them as my Spyder is set down to 4.2 or 4.3 now and as soon as I touch my gas pedal the car is moving there's almost no slipping on take off. But I've set up quite a few cars recently and noticed that almost none of them have the exact same KISS point. My GS is set down to 4.6.
Now for why you have to make sure those friction discs are properly warm.
After I set up the Spyder and I thought the disc were sufficiently warm, I took a good 30-45 min drive to my in-laws. On the way back home I was on the highway and putting the car in neutral then back into gear checking a few things out. The car was struggling going back into gear. It would only do it after I continued hitting the up shift about 3 times. I plugged it in and checked the gear box rpms, and sure enough it was dragging off the flywheel not letting it get into gear on the first attempt. Not good after installing a brand new clutch in the car! All is well now of course.
Anyway so if you want to get the absolute best KISS point tell him to follow this method for your car in the future. If you talk to Aldous Voice much, or you run across any of his threads he's commenting in, you can thank him for the information. I collaborate with him on F1 issues and he's not only a gentleman, he's a crack shot with these cars. I'm pretty certain, and I know this is going to sound a bit proud but I will risk it in order to give credit where it's due. I'm pretty certain I'm one of the best F1 techs in my area because of him. Funny thing is, I've never met him in person! Additionally this is the method Chris is describing to you.
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