Your firewall shouldn't drop this, it's on this site....
Spark Plug Guide
Figure about $50 for plugs at
www.RaceandStreet.com Look under "store" and then under "performance parts". FREE hat or visor with a $75 purchase.
Seriously, we all use Race & Street for parts. Fast shipping (sometimes free) and great personal service.
P.S. since you have a 2001 (like mine) the hardest part will be taking off and putting back on the EGR pipe that's attached to the back of the upper manifold. Read the instructions carefully and it can be done without too much trouble with the right tools.