The colours that I used were all from the Tamiya Enamel range and the process that I used was as follows:
- X32 Titanium Silver Base coat
- X23 Clear blue around the main areas where the staining is found
- X16 Purple in bands next to the clear blue and blending in the blue/purple
- X24 Clear yellow bands next to the purple again blending in the yellow/purple
- X19 Smoke spray a fairly dark coat over all the bands etc to just tone down the colours a bit
- At this stage it really looks more like Joseph's Technicolor coat that a Suzuki exhaust pipe!
- "Mist" coat X32 Titanium Silver this time very diluted about 1 part X32 to 20 parts thinners (Enamel thinners)
I misted the silver by looking a pictures of the Suzuki exhausts and where there was heavy discoloration I did not apply any X32 and where the exhausts should be silver I put down a heavy coat of X32 but again keeping it light here and there to let the blues and yellows shine through in some areas 
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I think the end result was a "lot of luck" and not sure if I can get it right again, sometimes with modeling you have really good days and sometimes off days where nothing works?
