Had a Shark remap a few days ago & was planning to fit the yellow spring into my Forge DV over the weekend.

I've taken the yellow spring out of the box & the yellow paint is a bit flakey & can be easily scratched. My question is: is this a problem, or is that side of the DV sealed away from the turbo etc? Obviously I don't want bits of paint going where they shouldnt.

I know I'm being a numpty here, but I'm assuming its just a sealed piston?

Depends... when the piston is fully pushed outwards by the spring, can you see the spring at all if you look in the side port of the DV? If not then there should be no risk of flaking paint getting into the intake system. If you can see the spring then paint could get into the pressurised side of the intake and either get stuck in the intercooler or make its way into the engine and get burnt off (best case) or get pushed into the pre-turbo side of the intake when the DV opens and get sucked through the turbo next time it spools up (worst case)

If you're worried about it you could always just remove the paint from the spring, I don't think it serves any purpose apart from telling one type of spring from another.

Get in touch with forge, or the place you bought it from, about it. I don't think it will be a problem to use it, but it shouldn't be like that.