legacy b4 front brake disks???

ok the disks on my 01 legacy are the drilled and grooved ones,i was driving home today and this awfull screehcing sound coming from the front right wheel sounds like a pebble got stuck in the pads,,took off caliper and check pads and cleaned everything, ,didnt find anything,put copper grease and all.back down the road and the screeching comes back but it only starts making noise when they get hot under heavy braking,when there hot they will start makin noise but when I brake it goes away?? my mechanic now thinks that my disc is warped.would warped discs make that awfull scratching sound??if so would it be best to fit standard discs back on instead of new drilled ones as i only put cheap pads in anyway.???which of these would be best?is the 294mm the correct size?
http://www.ebay.ie/itm/SUBARU-LEGAC...arts_Vehicles_CarParts_SM&hash=item256249022c
http://www.ebay.ie/itm/Subaru-Legac...arts_Vehicles_CarParts_SM&hash=item3a6c8a3839

Can anyone shed some light on this?

warped disks wouldn't make that screeching sound, I assume there's loads of meat on the pads and there's no low level warning clips on the pads that would squeel when the pads get low?

no pads are good,had it on the lift,spin the wheel and checked everything,theres nothing else that it could be???there is some black rings that ingraved itself into my disc since the last pads change,although it still feels fairly smooth!! duno why this happned but this might be causing some problem when the disc heats up?should i go with these groved ones then?they should fit i guess?which ones would fit?does the diameter have to be exact???
http://www.ebay.ie/itm/Subaru-Legac...arts_Vehicles_CarParts_SM&hash=item19c941a67c
http://www.ebay.ie/itm/SUBARU-LEGAC...arts_Vehicles_CarParts_SM&hash=item256249022c

i rang my autofactors,they have set for 80euro which is ok,i just need to measure disc now and see if its 277mm or 295mm,im nearly sure there 295mm....

If new Discs dont solve the problem I reckon its a wheel bearing.

No way Is it warped discs unless ya have a vibration under braking
My impreza screeches when at low speed but not at speed it the anti rattle springs that I believe is the cause of mine as the new ones are sitting in the glovebox
If that doesn't cure mine the hard mintex pads are going in the skip

im 99% its my discs now,i had a good look at the one thats makin noise,its badly worn down and a lot of black rings inbeddeb into it,feels a bit rough to toutch so i reckon when they heat up it starts rubbin on the pads.ive new ones to collect tomorrow so get them it this week and hope for the best!!!

If you do think its the disc then yes 295s are the ones! Though I though it was 294mm

Sounds like you need new discs anyway from your description