My -6 has PMB-rebuilt 911SC front and rear 914-6 calipers (from just back in December 2014) with old braided lines, a 19MM MC, Porterfield R4S pads, and an adjustable KH brake proportioning valve replacing the stock Porsche unit. I found today that the braid on one of the lines has fatigued and broken so I need to replace the lines immediately. The braking "bite" is not what I like so I'm looking to improve it but maybe a new MC will help if this one is leaking a little (just saw this today).

So.....

1) Would you replace the braided lines with more braided lines and then keep a watch on them and replace in another few years or go with good quality (ATE) rubber lines?

and

2) would you replace the stock -6 19MM master cylinder with a new 19MM or move up to a 23MM because of the larger SC front calipers?

I'm hoping Eric will weigh in here and give us all the straight scoop.

This is a stock 2L -6 for driving and some AX (7s & 8s x 16 Fuchs).

Rubber lines
Larger 23 mc will provide less power and be very stiff.