From Car and Drivers 1999 issue.
Quote:
Previously, the upper intake manifold plenum and runners, along with the secondary intake ports, got the honing; now the primary intake ports are honed, and the upper intake gets an even more aggressive application.
Regardless whether they did or didnt do a second round of EH'ing (which I do believe they did), obviously more aggressive EH'ing means there is difference between the 98 and 99-00. Nuff said.
Read the full Car and Driver article here 
