....differences after cleaning?

Not me. Terminally dirty fingernails and satisfaction of cleaning up a mess. I did this on my 240D when I removed the EGR and its manifold and put and old one on. I have never heard any reports of performance improvements but I will eventually get around to it on both my turbos anyway

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)