Few things to consider
- go slower with the gearing, use 15T clutchbell. This will give you better acceleration. This makes a big difference. Top speed difference sometimes is almost unnoticeable!
- try tyres with less side-bite. Bowties all around or Crimefighters front / Bowties rear. This will give more lateral grip to front and take it away from back - makes the car rotate around the corner easier
- tyres overall make BIG BIG difference. Maybe you are running too hard or too soft compound? Very big difference on how the car handles and feels.
- try 5-5-5 or 5-5-2 diffs (depends on your driving style a lot to be honest)
- try different brake balance. On very loose tracks it is sometimes helpful to lock the rear wheels and loose the grip that way. Works nice with drivers with less experience. Faster guys usually don't go that way
On some tracks brake balance makes a huge difference on your driving
- try thicker rear anti-roll bar, which should transfer a bit more grip to front (often not really noticeable)
- move the battery up front (the trend for 2011!). Need a little DIY and a suitable battery.
- read the Xray setup manual and find all the little setup things that make the difference. You'd like to have more front grip and maybe loose some rear grip.
A good tip is to get a friend who watches you drive for a few laps. Let him look for excessive wheelspin (give less throttle) and if wheels are locking somewhere (reduce braking amount or change balance). For an example with the 4-jump section often guys give too much throttle, have wheel spin and for that reason can't accelerate to jump it 2-2. And usually you don't want to lock up the brakes also.
Consistency comes only from practise! Try the VirtualRC simulator also, you'll be surprised how much it helps! On track you need to find the right pace for yourself - lets say 90% of the speed - so you can go consistently fast. Don't try to break the lap record every lap
Let others watch you run and ask for tips and tricks. Run with 1-2 guys together. Then you'll see where you loose and gain time compared to them. This is the best way to practise.
Hope you'll find something helpful here