cleaning stubborn old silicon dust inside of intake


Mar 12, 2018
e90 LCI 335i
Have to smog my car after a year to renew registration (CA DMV states I have to smog my car every single year now instead of every other?), so I have to put back on original location inlets I had sitting in my backyard for the past couple years. Scrubbed the outside and near the ports as far as I could, let it soak in a dish soap bath overnight and scrubbed again, I can still see visible silicon dust on the interior of the hose. Worried about this destroying my year old turbos, does anyone have a method to deep clean the interior of silicon hoses? I will run a microfiber towel through the entire hose but that won't hit everything.