I may well be wrong, but I don't believe that REVO, Superchips are actually writing or rewriting the code, they are simply adjusting the parameters, boost pressure, fueling etc.
As such they would not be not changing anything that belongs to the manufacturer and infringing their interlectual property rights or patents.
This is what I think too, although it's probably a simple copyright issue rather than patent. In any case it is not illegal for an individual or a business to purchase software (or hardware for that matter) and pull it apart to obtain knowledge through 'reverse engineering' the product, then use that knowledge in their own products - the car manufacturers themselves do it.
Remap warranties are always separate from VW's own warranty. It is the tuning companys agreement with VW for them to honour the factory warranty on unmodified parts which is so valuable to us as customers. To my knowledge that is only available in Europe and the UK from Abt and even then is dependent on the retailer/dealer supporting you as a customer if something goes wrong. In practise the likelihood of failure of another part on the car is very low and if you are unlucky enough to have a problem you can usually sidestep the issue (unless it's something expensive like a DSG failure).
For reference, I took this from the VWR website:
"Is manufacturer's warranty affected?
Yes, for those aspects of the engine and drivetrain that the manufacturer can prove were affected by any upgrade, any warranty claim will be rejected. All other aspects of the vehicle’s warranty should remain unaffected. Any parts from our range that are faulty or incorrectly installed will be replaced by us. Please note that this range of parts is intended for use within the United Kingdom, if you intend to use the car elsewhere it is your responsibility to establish the situation with regard to your manufacturer/other warranty."I can imagine some dealers will try to aviod getting into this situation (having to prove any failure is or isn't caused by modifications) by not touching remapped vehicles inside warranty in the first place - it's not an efficient use of their resources. Others might be happy to keep quiet and do the warranty work without question as VW pick up most of the costs. Plus if they don't know the car is remapped or don't find out, you are obviously okay.
Whilst I'd like to think most tuning firms would help out (if only to maintain their reputation) I think in this economic climate many will do whatever it takes to avoid spending money on repairing your car if something breaks. Having said that, there are plenty of people on this and other forums who happily drive around in remapped cars (and use them hard) without any issues whatsoever.
I can understand that the peace of mind from having factory warranty is important to many particularly with the cost of DSG and labour rates. However everything in life is a risk and personally, I'd rather have more fun in a GTI with 270bhp than worry about what might break.