I talk to many NHRA tracks around the country every week. Asking questions and help the ATV asphalt draggers get in if over the NHRA ATV 60" wheelbase rule.
3 tracks listed below are going to let you in. If got no silencers. Thats ok'd too.
Kansas City International Raceway. Kansas City,Mo. http://kcir.net/~kcir/content/
Mid America Motorplex / Rolling Thunder Dragstrip. Pacific Junction,Iowa
This track loves having ATV's. ATV Wars every year. http://www.midamericamotorplex.com/2006/default.asp
Memphis Motorsports Parks. Memphis ,Tenn
This track is one of the largest NHRA tracks in the country.
Keep a eye on this track. Drag shows like Arm Drop Live does let ATV race. It will be 1/4 mile drags. http://www.memphismotorsports.com/