World of Outlaws Sprint Car Series Muffler Rules

2026 WoO SPRINT SERIES MUFFLER LIST
Volusia Speedway Park	Barberville, FL	Mufflers not required
Talladega Short Track	Eastaboga, AL	Mufflers not required
Magnolia Motor Speedway	Columbus, MS	Mufflers not required
Kennedale Speedway Park	Kennedale, TX	Required: WoO Muffler Rule
Lawton Speedway	Lawton, OK	Required: WoO Muffler Rule
Creek County Speedway	Sapulpa, OK	Mufflers not required
US 36 Raceway	Osborn, MO	Mufflers not required
81 Speedway	Park City, KS	Mufflers not required
I-55 Federated Auto Parts Raceway Park	Pevely, MO	Mufflers not required
Jacksonville Speedway	Jacksonville, IA	Mufflers not required
Tri-State Speedway	Haubstadt, IN	Mufflers not required
Knoxville Raceway	Knoxville, IA	Required: must use Schoenfeld 14272735-78
Attica Raceway Park	Attica, OH	Required: must use Schoenfeld 14272735-78
Sharon Speedway	Hartford, OH	Mufflers not required
Lincoln Speedway	Abbottstown, PA	Mufflers not required
Williams Grove Speedway	Mechanicsburg, PA	Mufflers not required
Eldora Speedway	Rossburg, OH	Mufflers not required
Knoxville Raceway	Knoxville, IA	Required: must use Schoenfeld 14272735-78
Huset’s Speedway	Brandon, SD	Mufflers not required
River Cities Speedway	Grand Forks, ND	Mufflers not required
Nodak Speedway	Minot, ND	Mufflers not required
Hartford Speedway	Hartford, MI	Required: WoO Muffler Rule
Plymouth Dirt Track	Plymouth, WI	Required: WoO Muffler Rule
Angell Park Speedway	Sun Prairie, WI	Required: WoO Muffler Rule
Knoxville Raceway	Knoxville, IA	Required: must use Schoenfeld 14272735-78
Huset’s Speedway	Brandon, SD	Mufflers not required
Cedar Lake Speedway	New Richmond, WI	Mufflers not required
Wilmot Raceway	Wilmot, WI	Mufflers not required
Attica Raceway Park	Attica, OH	Required: must use Schoenfeld 14272735-78
Eldora Speedway	Rossburg, OH	Mufflers not required
Ohsweken Speedway	Ohsweken, ON	Mufflers not required
Weedsport Speedway	Weedsport, NY	Mufflers not required
BAPS Motor Speedway	York Haven, PA	Mufflers not required
Williams Grove Speedway	Mechanicsburg, PA	Mufflers not required
I-55 Federated Auto Parts Raceway Park	Pevely, MO	Mufflers not required
Knoxville Raceway	Knoxville, IA	Required: must use Schoenfeld 14272735-78
Ogilvie Raceway	Ogilvie, MN	Mufflers not required
Jackson Motorplex	Jackson, MN	Mufflers not required
River Cities Speedway	Grand Forks, ND	Mufflers not required
Red River Valley Speedway	West Fargo, ND	Mufflers not required
Huset’s Speedway	Brandon, SD	Mufflers not required
Belleville High Banks	Belleville, KS	Mufflers not required
Dodge City Raceway Park	Dodge City, KS	Mufflers not required
El Paso County Raceway	Calhan, CO	Mufflers not required
Stockton Dirt Track	Stockton, CA	Mufflers not required
Bakersfield Speedway	Bakersfield, CA	Required:  DBA RULE  (Schoenfeld 14272735-78 is legal)
Ventura Raceway	Ventura, CA	Required:  DBA RULE  (Schoenfeld 14272735-78 is legal)
Williams Grove Speedway	Mechanicsburg, PA	Mufflers not required
Millstream Speedway	Findlay, OH	Mufflers not required
Mansfield Speedway	Mansfield, OH	Mufflers not required
Sharon Speedway	Hartford, OH	Mufflers not required
Lincoln Park Speedway	Putnamville, IN	Mufflers not required
Texarkana 67 Speedway	Texarkana, AR	Mufflers not required
The Dirt Track at Charlotte	Concord, NC	Mufflers not required