I bought a second hand 320i inlet manifold and opened it out as per the wiki. Make sure you jet wash the inside after. Got a 325i throttle body and cleaned that up. Then it all just sat for two years! Finally had some spare time so changed it over
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It was a good chance to have a clean in the bay aswell. I thought it was pretty clean but underneath was a lot of dirt.
I would be careful buying the throttle body because i think there are differences between some of them. Make sure they have the same tubes and it will be fine. You need the rubber elbow from a 325i aswell. I used the orignal afm although i read you can change it for a 325i unit and its even better. If this is true i dont know, might be worth a try but the gains are really noticeable anyway, right through the rev range. It honestly feels like an extra 20%. My intake manifold was pretty clogged up when i took it off so im sure putting a clean one on has helped too.
The wiki guide still leaves a lot for you to work out yourself so if you have any questions just ask