remove carbon from pistons?

[foyster@xxxxxxxxxx]

I am replacing the head on my m20 with a rebuilt head. There is no wear in the 
cylinders but the pistons look pretty sooty. Is it a good time to remove the 
carbon deposits from the top of the pistons? It seems like some material would 
fall down beside the skirt, which would be bad. Perhaps it would be better to 
just run some fuel additive, which I haven't done for about 20,000 miles.

TIA,
Greg
Foy

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