My sons 400 Dart pictuted here has run 11.40's @ 117 with the stock 5/16 fuel line as he has just not got around to changing it. As long as the rest of the fuel system is ok you can run in the 11's with a 5/16 line and as said some run in the 10's with it. Of course a larger line always helps but for a 12 second car the 5/16 line should do the job. Good luck , Ron
