I just made this to help you if possible, bear in mind, i did it in a few minutes and ran 8 laps at spa..
My jaguar, is fully broken, without an oil change or engine rebuild, and has 550pp.
I everything BUT: JUST stage 1 wheight reduction, and use the semi-sport titanium exaust. Use the power limiter if necessary

And buy rigidity improvement also..
Aero: none
Ballast: 60kg in position +50
1- 2.604
2-1.8970
3-1.447
4-1.143
5-0.931
6-0.784
Final Gear: 3.350
Top Speed: 340kmh
Top speed in up right corner: 340kmh
LSD: 6/17/12
Suspension:
-25 -> -23 on rear
11.0/7.0
6/5
6/3
3/1
2.3/2.8
-0.12/0.17
Brakes: 6/7
Comment: pay atention to the wheight transfer... its a very heavy car so, brake early, and be gentle with it.. Its FOR ONLINE USE the tune. In the big straight from SPA i was reaching 270kmh~.. its good.
Its not all that slidy anymore also. Another sugestion, is for a similar car, is the e55 amg that i have tuned on my garage.. try it also..

Hope i helped you..

say something if you can..