Depends what car they drive

If I'm in a situation where I'm getting lapped I will let off the throttle at the end of the straight and move over a lane or so. Then say "inside" on the driver stand to whomever is lapping me.

Why? Their faster, no reason for me to hold them up. Most of the time I can follow them for a couple laps and find out what sections of the track I'm slow in. You'll be amazed how a little track courtesy will go in the pits when you need something.