With your New exhaust & other Mods, I think you are best off Putting the Hybrid at the Top of the List (should be done before any Mod IMO), I did follow this route but, just had some bad luck with the guy who sold me the 2nd hand Hybrid which had Play in it (he ran it just over 1k, & his car wasn't even mapped, so surprising as to why it failed).
I had my exhaust and other mods fitted at the same time when fitting the hybrid. But due to the above reasons standard turbo had to go back in, and at that time, it was fit as a fiddle, seemed solid no play or anything. I didn't have monies to replace the Hybrid so I drove for no more then 3k (if even that), and the standard turbos packed in. The standard turbos are rubbish as we all know. Any mods that gives you gains is naturally going to decrease the life of a turbo (and in this DCi case and mine even more so then any other Tubo'd motor).
I do have a Turbosmarrt FCD2 Fuel Cut Defender, which I don't think I will be using anytime soon if either of you fella's are interested.