want some opinions if this makes a difference

 

Depending on how bad the lines you replace
are, you may get a slightly sharper initial
pedal feel from steel lines, because their
modulus of expansion is lower (ie: they expand
less for a given pressure), but this feeling
would only rise above the placebo effect if the
lines you replace are relatively bad. The
difference between a well-bled, fresh fluid
system, and one with older fluid or one with
a little air in it, is probably going to be more
noticeable. Unless there is the slightest concern
for the condition of your current lines, I'd try
a service with fresh fluid first, and see if that
didn't perk the system up enough.
Joe

 

I have steel brake lines and I guess all the debrie from the manufacturing of the part wasn't completely cleaned out of the lines so after about a week of install all my brakes locked up ... so the service rep said ... warranty replaced some master brake something and now they work fine?

 

On the street it helps only marginally. On the track, when the brake fluid (and consequently the lines) heat up and expand, it makes a bigger difference.

 

This is what my tech told me back when I first got my TT: "Unless you are planning to track the car extensively, there is no reason to change the brake hoses. They are fiber reinforced rubber. Steel hoses look cool to anyone under the car, but there is no advantage for street use and only marginal for track.The steel mesh limits the expansion possibility and therefore helps to reduce "fade" from prolonged high speed/high temp braking conditions."