Just as a matter of interest what tyres are you running? Are they the same others are running in the same conditions?
Have you tried things like more rear toe-in, softer rear springs, longer rear camber links, saddle pack battery placement, switching the front wishbones to run them on the "wrong" side, more front tow-in, etc.
You could also try turning down the steering curve on your transmitter or turning down the brakes on your speedo as a last resort too.
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