Ideas to replace Coreloft in Atom SV?

maybe rip out the seam at the bottom, slip in 2 foot square of synthetic insulation. sew through both sides of the fabric and the added insulation around it's perimeter to keep it from shifting. Then sew back the seam you ripped out

I don't believe you can pull out the insulation because unlike the NanoPuff, the Coreloft is laminated to the shell fabric and not stitched to it. The laminated insulation is what set the Arc'Teryx synthetic insulation pieces apart from everyone else in the industry, that and its highly hydrophobic properties.

don't remove, just add new insulation. maybe thin insulation like 2.5 oz apex if you asked someone for a piece of a specific size, i bet someone would send you a piece. I have lots of scraps. I've thrown some away, but really need to throw out more. I'd just ignore it. It drapes down on the back usually leaving an air space so there's still warmth. Small area.

Have you contacted Arcteryx? They are usually really good about keeping customers happy.

I appreciate all the replies (I forgot I'd posted this…) I think I'll eventually use 2.5 Apex as recommended, and try to layer it over the original insulation. Jerry, you're right I should ignore it for now. I've been babying this jacket ( never driving or sitting around with it. ) I think I'll stop babying it and prepare to modify it next year. Thanks again.