Will DLS R5A 13.5 Speakers Fit in the front Doors A3 8l?

No you can't go deeper than about 54mm. I wouldn't spend that sort of money either as the quality is seriously compromised by the flimsy door cards loosely clipped to the doors. If you want dramatic improvement add a proper sub.
 
Thanks mate for the reply,
Already got a sub in boot, but wanted to upgrade the doors with these mids that I already have. Is ther now way to mod the doors for them to fit?
cheers
j