This is an interesting debate on the nature of what is "stock." I can definitely see both sides of the argument. If something can be loaded by any user with the stock game, then there is certainly some merit to the idea that such a craft is stock. For example, craft built with EditorExtensions can have things that the stock editor does not allow, like symmetry greater than 8x and surface attachment for parts that do not allow it by default. I personally consider such things to be stock. I don't think it can be compared to clipping though, since that is allowed by the default editor. So my question about doing this, because I'm not entirely clear: are you adding solid fuel to the SRB in the craft file?