Hey there, glad my blog is helping. I'll see if I can answer some questions.
Turbo Reliability - We delete to help the turbo. I believe heat is more detrimental then spool speed. The tune should keep the spin rate at a safe level to not put added stress on the turbo. Speaking from my 1st tune before deleting to the 2nd tune after deleting. The EGT reached alarming temps with the DPF intact with a minuscule 25 extra hp. The 2nd tune after the DPF delete, the car handled an extra 55+ hp and 75+ trq while keeping EGT temps at the level of the stock car. We could of pushed it more but I wanted to stay conservative. I love that the temps are lower with the extra power.
Black smoke - At first there was an alarming amount of thick black smoke. Within a few weeks of driving that eased up to the point I only see a cloud on WOT redline runs. If I try to make a quick lane change and give a little extra (not WOT) I might get a slight puff.
+FYI - I'm using ULSD #2 Diesel in my car. This produces more smoke then Biodiesel. I have added Standadyne Performance Formula 8 oz every other fill up and noticed a considerable reduction especially on the lane change type moves. Prior to it, the smoke would of been more noticeable. Not sure what you'll be using.
Diesel Smell in Cabin - Rarely is this noticeable and it is only when the windows are open and the wind is blowing in a specific direction or no wind at all and I'm sitting at a light. Again this is only with windows open. A quick remedy, throw the recirculating air, AC, or heat on, and the smell is gone. I do not get any smell with windows closed. If you are getting it in the cabin, something is not tightened up properly and allowing exhaust into the engine bay then into the car.
Swirl Flap Delete / EGR -
https://www.clubtouareg.com/threads/t3-tdi-intake-swirl-flap-delete.288285/
Only thing I could really find. A lot depends on your car. For my A6, there isn't a block off plate to purchase. The EGR is tuned out and stuck shut after speaking to the shop, Buzzken, and Rawtek. The swirl flap is another non-necessary delete from reading around. I'll add, my car has a setting to create heat for the car using the diesel. Its in my MMI settings. I've switched it on. I can now get heat fairly quickly from a cold start by setting heat to High, 12 for power, and recirculating. I can even warm the car up in the driveway now which I thought was going to be useless after the delete and the car not moving.
https://www.audiworld.com/forums/q5-sq5-mki-8r-discussion-129/q5-supplementary-heater-2893397/page2/