on the power level you are trying to make. With running twin 485 pumps stock lines wont be enough if you want to use their full potential. With the pics I posted I ran an -8an line from the top of the Y all the way to the fuel rail. This will flow plenty of fuel and if you use a trigger for the 2nd pump the stock return lines will be fine. You can also use what was the main feed line for the return after running your new -8an.