I noticed a number of posts in this thread about how the DSC comes on much more after the tune. I hope people realize that all this means is that you are not really getting the extra power to the ground. So what if you have an extra 12-15 hp? If you don't have the traction to take advantage of it, the DSC/traction systems will just cut the power to the wheels.
The M3 is already traction limited in lower gears with the stock ECU programming. The real benefit here is the subjective feel of the power band, and how the car may be able to pull in higher gears, where traction is not a concern.
So....don't be so happy about your DSC light kicking in more. Be happy about how much better your car feels in general and how it pulls at 80mph when you down shift and punch it.
And yeah.....I haven't done this yet, but I've just heard so many great things about the tune, both online and in person, that I will likely take the plunge too. I really don't care about the added hp, as the objective benefit is trivial. I do care about how it makes an already great feeling engine even that much more enjoyable in its power delivery.
Audi S6 * Audi S3 * Porsche Cayman GTS
--Former BMW M3 owner