hey mate, what tools/materials did you use to clean up that inlet manifold? Looks like a job well done!
firstly i went over it with a wire brush to get oxidised alloy off to see if it made it look any better which it didnt, so then i went over it with a very course sandpaper one you use for rubbing down bodyfiller it was all i had making sure you cover everything that alloy dust can get into up ie air filter, alternator etc i also pulled out dipstick and put a rag down it as was easier to rub down, then you will start to see certain areas start to shine and will have dark bits you need to rub down to past these bits as these are casting marks, this takes ages and being on the car makes this even more harder, once you have got everything nice and shiney i started going to a more fine sandpaper this takes out the scratches you leave with the course paper sorry cant remember what paper i finished with might have been 800 i think as i have a bucket of mixed papers, now i used to be in the bike scene and bought a polishing kit for aluminum and stainless steel which comes with two polishing wheels a buffing wheel and rubbing compound of diferent grades, then i used the brown rubbing compound which i believe is the course one and went over it with that which takes out the remaining rub marks left by sandpaper and the finished with everybodys fave the solvol autosol and buffing wheel, as said it not perfect but looks a whole lot better once im out of hospital no doubt i will have another go to get it more perfect.
this is like what i bought and is good to have as the things ive polished with mine is unreal, bike frames, swinging arms, wheels, heatshields, exhausts the list is endless if its a shiney metal you can polish it, got me out of the brown stuff with the wife as i scratched my wedding ring big time and buffed that up with it and took all the scratches out of it, one of those things you dont use much but is very handy to have indeed.
http://www.ebay.co.uk/itm/Metal-Polishing-Kit-4-Aluminium-Brass-NFK0-4001-/300417343941?pt=UK_Motorcycle_Parts&hash=item45f244e1c5