^^ As above.
It depends if its been painted in 2k solid or base and clear.
My Milano DC5 was 2/3 painted in 2k solid so alot of that was recoverable from fade. The other 1/3 had been painted in base & clear so was shiney anyways.
Red by nature fades, its the pigment in the paint. Its just really opaque. As are alot of other solid colours, blue, green etc but red it worst.
If its painted in 2k solid then you're actually polishing the paint it self & by using some cutting compount you're removing the old, shitty, faded paint on top to get to the nice shiney red underneath.
If its been painted in base & clear then the red has faded under the clear laquar (mainly down to poor base/colour coat or cheap laquar with no UV protection in it). If this is the case, you have no chance or recovering it.
How to check, get some compunt on a rag and give it a polish, if the rag turns red, its 2k colid, if not, its base & clear.
I'd suggest Frecla G6 for a first timer, its a good product but not as aggresive/rubbish and G3.