Shortened the back lines on the 5 and 4.3 by about thirty millimeters. It gives slightly better pump ability when getting up on foil. There is probably a small trade off in upwind reach...maybe...I do not know 100%. But it most assuredly pumps better. The easiest way to test, is to fly the stringwing on the beach and use one hand the just slightly pull the rear lines in. You should immediately feel some difference. It will not be much but you will notice it.

Huh... nice! And easy to do and switch back or tweak/tune.
I just shortened my bridle on my PR 3.0 by 15.25 cm / 6" using the temporary wrap method and I am really liking it. I was really hesitant to mess with it, but I am glad I did. Out on it 4 times now in different con editions- light to lit and it all seems to be upside with no negatives I can see. No detectable decrease going upwind or with the wings behavior, handles jibes more nimbly. It may be my imagination, but feels slightly more solid pumping too. Of course the biggest + is stowing which is night and day.