Ticking sound from engine 2004 Dodge Stratus SXT?

It has 87,000 miles on it and I just bought it this week. The guy I bought it from said it was a lifter noise. I took it in to get the brakes and rotors changed and the guy that test drove it after they were done (he's a certified mechanic) said that it sounds like an exhaust leak because the sound gets worse as the rpm's get higher. What should I be listening for and is this an easy fix??