While quite fast and a nice drive, it's not worth buying the 380RS. You can win it as a price car from an event. I can't really remember which one, though...
I'd be happy to share my setup, but keep in mind that it's not fully upgraded since I've been using this car to race in 404hp or less events online. That being said, this car is a handling beast straight stock, so I haven't modified it too much.
One of the main things I noticed about this car is that 5th and 6th gears don't have much torque at all. At first, I couldn't even get the rev limit up in 5th gear for this thing, so I have the trans set at a very low top speed, just to increase acceleration and get actual use from the higher gears.
Aero: 20/35 (can be lowered for more speed)
Engine: Stage 1 (405hp)
Trans: 162mph
LSD: 15/44/25
Height: -5/-5
Springs: 12.5/11.3
Ext: 7/7
Comp: 7/7
Roll: 3/3
Camber: -2.0/-0.8
Toe: -0.12/0.20
Brakes: 2/1 (personal pref., I don't usually use ABS)
Tires: Racing Soft
I'm usually contending for first in the online events I mentioned with this tune. Like I said, it handles great and I haven't spent a ton of time with the suspension. Probably actually better idea to lose the negative toe on the front and to adjust the dampers and roll bars to adjust understeer. Hope this helps.