Help with tuning on GT3

[JR98]

I haven't played GT3 in years, and never tuned my cars when I originally played it, and I just bought it again. Could someone guide me to good tuning strategies on the game? I have done just the Sunday Cup and have started with a 1989 Mazda MX-5. It is completely stock and it is pretty much impossible for me to win the Clubman Cup in it or my 86 as the MR2 is just too fast for them, I come second every time. If someone could guide me with the best tuning parts to buy, some tips on tuning cars handling and transmissions and a few other things. Any help will be greatly appreciated.