Sprint booster was covered a while back when 100% asked about them. My opinion then and now is that they are a complete waste of money. I got one for my other car and took it off after a short while as it turned the throttle into an on/off switch. I've since sold it on via a forum and the guy who bought is is raving about it. Make sense of that.
I think you're throwing your money away but don't let that stop you.
I don't see how the TÜV approval would apply to a custom map but I'm not going to lose any sleep over it.
Edit, I've just had a look around their site and some of their statements seem a bit tenuous to me. Like the claim that a re-map "shouldn't" affect your existing warranty. I wouldn't like to put that to the test.
I can't find any T&C for their 3 year warranty, personally I'd want to study that in detail before handing over any of my hard earned.
I had the same concerns .
My understanding is -
The TUV is obtained by sending the software off , to be checked before being loaded to the vehicle .
As for the remap not affecting your warranty i think this is due to the fact it will be very unlikly to be found due to being custom meaning the file name the same ie merc name and not the tuner name.
Please correct me if i am wrong (this may not be 100% correct please check with GCL)
Clive