This is going to become law:

""Certified motor vehicles and motor vehicle engines and their emission control devices must remain in their certified configuration even if they are used solely for competition or if they become nonroad vehicles or engines”. 80 Fed. Reg. 40138, 40565 (July 13, 2015). ""

If this passes, aftermarket parts producers will be heavily fined--potentially killing off smaller aftermarket parts producers (exhaust, ecu tunes, etc.).

Petition to the WH:

"Tell the EPA to Withdraw Its Proposal to Prohibit the Conversion of Vehicles Into Racecars
The American love affair with automobiles includes watching and participating in motorsports. For decades Americans have converted their street vehicles into racecars, from pre-World War II classics to modern era performance cars. It has brought joy and jobs to millions. However, the U.S. Environmental Protection Agency has issued a proposed rule that would do away with this time honored tradition. It would outlaw the conversion of any type of emissions-certified vehicle into a racecar, and make it illegal to sell any emissions-related parts for those cars. The Clean Air Act prohibits the EPA from regulating racecars. Tell EPA Administrator Gina McCarthy to remove this provision from the “Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- & Heavy-Duty Engines-Phase 2" rule."

Petition: https://petitions.whitehouse.gov/pet...les-racecars-0

Articles:
http://www.motortrend.com/news/epa-p...s-to-racecars/
http://www.regulations.gov/#!documen...2014-0827-1469
http://www.autoblog.com/2016/02/09/e...sema-official/