Here's a crash course to learn to tune, if you want to master them, start with the small cars like an evo or sti for the awd class and from Ruf RGT to cudas for rwd, if you can achive at least on .020 difference from top time then you have a good tune, what i used to to was retuning the whole car if a tune didn't felt right and start from scratch, it helped me learn all possibilities and it should help you too. Also, having the fastest time on thest it does not mean its the fastest online, for example; my enzo runs a 9.000 but online pulls like krazy, same with my le mans quatro with a 8.901 and my ford gt n.s. with a 9.045, in some cars are different like my ZZll its time is 9.001 but it grips so much at launch that even if you pull, won't be enough, my advice for you is, when you tuning a car after seeing its specs, you have to feel if the tune is right or not, the answeres to each individual tune is at each individual car performance. Good luck and Happy tuning