Did the pipe and the manifold myself:
Obviously get the additional items and mask over all holes; Start with 120 grit, working all the way up through 200 (use a drill with a sanding disc up to here with a firm grip on the pipe/manifold),400, 800, 1200, 1600, finally to 2000 wet and dry. Spend at least an hour on each grade. It'll still look cack at the end though. Finally finish with Autosol (NOT Autoglym, Peek etc - HAS to be Autosol) - It then comes alive. Keep gong till no more black stuff comes off on your stockingnette polishing rag. Then move to supersoft polishing cloth.
When you think it's as clean as its going to get, pre-heat your oven to 180 and send your other half out of the house. I kid you not - trust me, its easier this way. Bung the metal in the oven for half an hour. What this does is bring any crud that's imbedded in microscopic scratches on the surface. Clean off with spirit (This negates the 'just fitted, first drive, 'OH MY GOD, MY SHINY STUFF HAS GONE GREY!' screams). Obviously let it cool first, but clean when it's still warm, not when it'll burn our skin off.
Finish again with a thin layer of Autosol and a fine polishing cloth. Some people laquer here, but they're Wusses. Job done.
Should easily do it over a weekend.