I'm having an issue whereby the SVG I export via print composer doesn't reflect what I see in QGIS. My exported SVG image collects additional grey borders around the outermost boundaries of the raster.
Here I'm having the same problem with a different raster, on a different computer. This is QGIS Release 2.18. You can see my workflow below.
Exporting to SVG or PDF using print composer has a grey border each time