Wow, ace, been a member for 8 months, but this is your first post? Welcome to GTPlanet.
Try this modification list:
* full race suspension
* sports brakes
* brake balance controller
* stage 1 tune-up
* full engine balancing
* sports chip
* full race transmission
* triple clutch
* race flywheel
* full LSD
* medium-slick tires (T4)
* lightweight 1
You could maybe delete the engine balancing and the lightweight work, and go with Stage 2 power. Balancing and Weight reduction can't be removed from the car, and some races require a stock car, with only tires and oil allowed.
Here are some suspension/drivetrain settings to try:
Spring Rate: 10.8/10.7
Ride Height: 55/70
Bound: 4/5
Rebound: 10/9
Camber: 3.0/1.5
Toe: +0.5/-1.0
Stabs: 5/5
Brakes: 23/24
LSD: 15/30/15
Auto Set: 30
FD: 3.680
Downforce: 0.29/0.60
ASM: 0
TCS: 2