The calculator: forums.forzamotorsport.net/forums/thread/4859908.aspx
How to use it: www.youtube.com/watch?v=by7JDh-5Y1g
The guide: www.2shared.com/file/E_EpJMTO/Forza_Motorsports_Tuning_Guide.html
How to use it: www.youtube.com/watch?v=jinIpYN1zyU
Hope you enjoy it!
Tip: make a tune for every track because it happens sometime that a perfect tune on one track is worthless on an other track, so like i said, have a lot of patience and you will have those perfect tunes for sure =)
[Edited by Infexis, 12/31/2011 4:21:11 AM]