hi all i'm having a bit of a problem with my m03 i'm hoping someone can help?

Two weeks ago my m03 was planted i could nearly go flat out round the corners and it would go flat out down the straight and would go straight as a dart i was well happy with it, now its still great round the corners but as soon as a i put the power down the car goes to the left. i've looked all over the car and find nothing wrong.
i'm running 17.5Bl with a Ta03 ball diff,any help would be great

Cheers Ginge