Make sure they are hand tighten and another 1/2 turn on all rubber parts or else it will leak again real soon. On some of the European stuff like Hans Ghroe, that piece of connection between the pull out flex line and the rigid line must be hand tighten only. ASk me how I know. don't be like most contractors, read the instruction if its one of those high end faucets. I read every single one of them if its something we don't often install.
Cut out the sill? This is not your new kitchen is it?
