I prop should have got better underlay looking at the floor now, but i've already bought it and the flooring (so no carpets going down TF rallyesport) I have thought about sanding it but trying to save money so don't really want to hire a sander, plus the room is already painted and that sounds a dusty job, theres no loose floor board's so i'm ok there,

And just to make things clear its side to side where the boards have curled making the gaps between the boards bigger , I know you wouldn't feel it once the floor's down but i want the floor to last and thought it mite allow the new flooring to move more and i'll be finding gaps between the planks in a few months time.

thanks for everyones help think i mite put some ply down to be safe,