Cowl fastners - firewall side plate

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I’m repairing a S7 that a purchased using new parts. Trimmed cowl and now doing the cam lock fasteners. On the sides of the lower cowl attaching to the firewall flange, do the cowl fastner backplates attach to the stainless firewall side plates (footwell sides)? Previous owner had attached the firewall side plates but they don’t extend aft far enough to take the cam lock back plates and line-up with the firewall flange above. I wonder if the cam locks actually just install in the glassfiber of the boot cowl and I need to trim the stainless to clear the backplates instead?

hope this makes sense, will do some pics if not.