First test out, .387 faster than stock suspension, trans, lsd, etc. I ran 20 laps with stock settings and ran a best of 43.398 with 43.401 backer. Your setup I ran the same amount of laps with a best of 43.011 with a 43.020 backer.
Im not a great driver by any means but im not horrible. I think if you (or I) can get the rear end a little bit more stable itll be faster. Also going to try shortening 5th gear a touch. I know im not considering the draft of other cars right now, but it still seems a bit too long. Keep ya posted.