There is a difference between when changing the gears itself if you can literally hear and FEEL a CLUNK vs. a bit of higher tone CLANK when letting out the clutch. The later is totally normal for the dual mass flywheel that may sound bad but actually makes clutch engagement itself very smooth. Now if the gears themselves actually CLUNK and you can feel it in your hand while shifting, then you have the aforementioned halfshaft issue. I hate to go deeper into this and tell you to change something on a brand new car, but part of the fix for that is using 2L instead of the factory 1.6L of gear oil. So one of the first things I recommend is switching to 2L of Ravenol MTF-2 gear oil. It actually meets the exact Ford spec for the trans and is FAR better than the grey and watery DCT fluid that I swear they decided to put in there because they had so much extra of it from the DCT base Fiesta and Focus they came out with right before the FiST. They must have said "Screw it, it will get them to 60k then the warranty runs out and we can get rid of this extra crap." I changed my fluid over at 12k and immediately felt improvement and has gotten better and better with more miles, before that I would grind gears, and have even good shifts "crunch" a bit. Now, only the very first 1st-2nd shift on a cold startup is a little rough, and that improves by letting the car warm up for a full minute before taking off, even though we really shouldn't have to. Otherwise the trans itself can handle lots of power, it's just the feel for it sucks with the garbage fluid in it.
