Autogas/82UL STC's. STC's for PA-28-140, -150, -151, -235 do not require changes to the fuel pumps or plumbing and sell for $1.50 per hp. STC's for the PA-28-160 -161, -180, -181 require modifications to the fuel system per STC SA2660CE. If you have a PA-28-140 that has been converted to a 160hp engine, then it will require the fuel system mod as well.
The Warrior II and Archer II and the 24 volt Warrior III and Archer III series are approved via STC SA2660CE for the use of 91 octane (minimum) automotive fuel. Piper Cadets are included too, the Piper Arrow however is not.