I have two TDI's, identical from a drive train standpoint, one has been Upsolute chipped since maybe 2000 and the other is stock. The Upsolute car will give a gas VW 1.8T a serious run for the money and get better mpg than the non chipped TDI (51 versus maybe 47). The difference in response is night and day, I really have to be careful not to redline it in lower gears. It is really fun to drive, much more fun than the non chipped car.Both my former TDI's were chipped, and it's a world of difference. It was astonishing how much better they were, and if you can keep your foot off the fun pedal, the economy's about the same.
If someone reputable made a chip for the CTD and the car was out of warranty, I'd probably go for it. You can also play with injector nozzles but as mentioned earlier, you can bump up against the limit of some of the mechanical bits at some point. In VW world, all that has been sorted so you know what combos are fun and what combos go boom. I assume the same will happen in time with the CTD.
I'm just wondering what it's like to actually have as much HP as a stock CTD to play with. I think my stock TDI is maybe 90 HP and the chipped car is 120.