I have a "Chip Switch" from Markus at PUK. works very well and has 7 programs. All you do is change the number via a switch, let the ECU relearn, and go have fun. So I could drive stock, 'high Torque', and S4S back to back. I have never driven the other programs on the switch which include the red race code and a 310 and 330 code. The latter are less safe for stock motors per Markus.
There is a noticeable difference. The S4s is very nice, and the high-torque absolutely gives more low end at the expense of a little high end. Either one is a significant improvement over stock, hopefully without stressing the drivetrain too much. I drive the two depending on what mood I'm in.
Randy