The Turbo Lag in the F40 is truly exaggerated:
When you upgrade it with the High RPM turbo. The turbo kicks in at 4000rpm and provides solid boost to red line at 7900 rpm. It's quite manageable, as even with the longest gears possible you wont be shifting into the turbo lag. Just keep in mind you need to shift down before 4000rpm.
And at the starting lines, hold the e-brake and rev the engine, drop it in second gear, then release your e-brake. The engine will bog to 5500 rpm and you'll take off with minimal tire wear and without turbo lag.
The correct settings for the F40 are actually surprisingly close to the settings that come standard when you purchase the Full Suspension Kit.
Ride Height to 20/-10
Spring Rate to 7.0/7.0
Comp. Dampeners 7/4
ARB 6/3
everything else at default.
The f40 can be very fast if you tighten the suspension up, but by doing so, you end up with a car that COULD go fast. But instead of going fast, it's is more likely to end up in a wall somewhere.
I prefer my cars to be composed and easy to anticipate.
Extremely influencable but yet easy to reel in once they've started to go.
Softer setting may cost you that one second or so, but the benefits of not hitting a wall, are well worth the cost in longer races.