NOPI Nationals in Atlanta is a huge one. Located at the raceway there.
I have been to 2 of them lots of everything there, but with the majority geared towards the import scene.
There are alot of different classes though, so each person competes against like cars with similar levels of mods.
Theres other things there to keep party goers interested, sound comp's, burnout comp, wet tee shirt contests
hydraulic contest
they usually have a dyno there for hp comp's.
Lots of high HP muscle up there!!
http://www.nopinationals.com/2k6/index.php