I usually just hold my line rather than moving around the track. If the car behind has a lot more power than myself they'll gun it around me down the next straight. If the car stuck behind me has similar power I'll ease off the throttle and point them in the direction to overtake me. It makes it clear what you're doing and what you want the other driver to do. Much safer than dodging around the track. 

Yes I get that problem as well. Not so much with evo's. They beat me just about everywhere. I usually get stuck behind something like a soarer or commodore. The only cars I can return the favour to are mx5's haha.