Can anyone advise me on this just had new pads and disks fitted 3 weeks ago bought from godspeed and also new wheels and tyres fitted 2 weeks ago
after a bit of spirited driving I noticed the front end gets a bit twitchy pulling left and right when braking heavy

 

You need to make sure the hub faces are clean and ideally you'd wanted to bed the discs in for a couple of hundred miles rather than stamp on them from the outset...may be warped a little but only a guess

 

I've done around 300 miles on the brakes and I cleaned the hubs and torqued the wheels up to 90nm as for warping wouldn't the cause more of a vibration

 

Sticky pistons on the calipers maybe? What model Subaru do you have or should I say what brake setup you on, and yes warped discs would give you the judder but the pulling could be down to brake dust accumulated were the pads sit on the calipers or the Pistons getting sticky hope you sort it let us know how you get on pal