1.8L intake cam: 1996-1998 Elantras and Tiburons
It opens 3 degrees earlier, closes 5 degrees later, and has 0.4mm more lift than the comparable 2.0L intake cam. Probably makes another 3-5 flywheel horsepower if combined with other simple intake modifications (throttlebody, cold air intake). It is visibly impossible to tell the difference, your mechanic would have to break out a micrometer and measure the lobes to know it was a different part than your stock 2.0L cam.
2.0L intake cam: 2001.5 and later Elantras (Elantra GT is what you should ask for)
Opens 7 degrees earlier than stock, and closes 9 degrees later than stock, along with 0.8mm more lift. The car doesn't like to idle "nicely" with this cam as the cam overlap is a bit more substantial. It probably makes 5-9 flywheel horsepower if combined with the FULL compliment of bolt-on intake modifications (bored intake manifold, bored throttle body, cold air intake). The problem is, because of the lift and duration, it makes that power further up the power band. It too is indistinguishable from the stock cam visibly, but the idle will tell them that <i>something</i> is up.
Part numbers are available from St. Charles Hyundai... Cheapest dealership in the world to buy OEM Hyundai Parts: (800) 727-8066.
-Red-