I have considered the use of engine flush many times but there are many conflicting reports of its use on a high mileage engine (mine has 98000miles). Some say its beneficial, others say it will stir up so much dirt that it will do more damage than good and it may clog the engine's arteries! Since my turbo is still functional, i am not too concerned about excessive dirt. When I change the banjo filter a year ago, the filter inside was still quite clean (which was a relieve).
About the inlet pennilum, do you have a picture, maybe the old vs the new? I have one of the latest pre-facelift model and a few things are in fact from the facelift model.
My focus is really lacking power and I noticed a new slight whine from (i think) the turbo. Not sure if its dirty or its on its way out but considering the type of damage you would get from a blown turbo I decided to purchase a refurbished unit from ebay for about 300 quid. Not wanting to spend much more on this car (repair bills in the last couple of years have run into thousands already), I am thinking of doing the job myself with my buddy helping me. Haynes manual put the job at 4 stars which I honestly have never done but have found 3 stars jobs pretty easy. I also have a good set of tools and pit in my garage. None the less it is still something that neither me or my friend have ever done - do you think we should do it or is it too risky?
Also apart from the gaskets, what else needs to be changed? The oil feed pipe was replaced a year ago since I decided it was a good practice to do it while I had my DPF being removed.