LP640 high speed problem

[s130z_eu]

I have problem with my Works upgraded Lambo.... Although i tuned it for fast tracks, max. speed is about 160mph. At this speed in 6th gear car doesn't accelerate (not even close to rev limiter). I hadtested it on Nordschleife a few times, then changed settings few times, but without useful results. Even stock lambo can pass me on straight lines.
Suspension setup is softer, and steering is decreased and tuned to have more stability on higher speeds. Downforce is also decreased, final drive ratio is high (about 5.2 or 5.3, 6th gear is 0.87)
Btw. I have similar problem with Works RX-7. Gearing works normally (gear ratio is on max acceleration, 1th,2nd,3rd gear on speed) but when i restart race, gears became too short, so it reaches rev limiter in 3th gear @50mph, 4th@62 mph.
After race I had checked my gears set-up, it were changed (shorted 1th, 2nd, 3rd gear, final drive ratio and other without changes).
Can someone help?
[excuse me because of bad english :S ]