The 380RS is comes fitted with Sports Soft. As it is already 100k, there will be no modifications. However, the driver is allowed to adjust suspension, as it also comes standard with sports suspension.
For other cars, tires are not fixed. If you think 36K into the tires is a good investment, go for the racing soft (not sure how much they actually cost, but you get the idea.) I think the cheapest Z is 36 or something so if you did that with race soft tires, you'd have spent 72k of your budget.
I tested the 3 premium Z's against the RS a few months ago using a d-pad and limited suspension tuning with the same 100k budget. I was able to beat my best time in the 380RS around a course maker track with 2 out of the 3 other Z's. The other was way off. They were all tuned a fair bit differently. I also spent much more time in the other cars trying to beat the time. If I had equal track time, who knows what the outcome would be.
As I mentioned earlier, I think I am going to hold a race to determine who drives the RS. Either prior to the actual race, or a few days before. If you want in let me know! To uphold the "chase" idea, I want to ensure the 380RS has pole position, but I don't want to handicap everybody elses starting position. I think I have a solution, but it is pretty complicated...I am going to try it later to make sure it will work.
Rabbit Candidates:
Capt Air
Bones Brigade
Madmyk