What br and are they? I upgraded to the Russel brand SS brake lines on my Fox and New edge. I've still got the drums on the rear of the fox, so its a thre line kit. But you definitely notice the spungyness is gone with the ss lines. They won't expand ir degrade like the stock rubber ones. Just make sure when installing, you check the clearance between the lines and anything they could rub on.
2000 Mustang GT-Former giggle gas addict
1990 Mustang GT w/ Vortech V3
***resident gun idiot***