[Buford427]

Ear plugs and Aviation Head Sets.
Ear plugs when I'm by myself or short runs with passengers and the Head Sets for longer trips.
My son and I brought the car home to Idaho from the Bay Area, 850 mile road trip and the Head Sets allowed us to carry on a "normal" conversation as well as pipe in the iPod.
Exhaust noise is not so much the issue as it is the buffering of the wind that kills your hearing. The pressure changes on the ear drum will make you deaf for short periods even on short runs.
Wear the plugs and though spendy the Head Sets are great.
Got mine on Ebay along with the "brain" box. Runs on 12V car source or internal 9V batteries.
Besides, they look cool.