Yea, I have heard the same thing... Asked a guy I work with about bringing the shine back to my trailer fenders (they are metallic gel coat also). He said the best way he knows of keeping the shine from going away is to wet sand them down (as you have) and then apply lots of clear coat (as you have). Looks good!
Need LT-1 parts?
OIL FILTER: Factory installed is a Penzoil P23, Afta market brands, AC Delco PF-454 and a Fram PH-13 or PH-30 will work.
SPARK PLUGS: AC Delco MR43LTS (gapped to .040")
FUEL FILTERS: AC Delco 25171391 (pump inlet side)
89058397 (pump outlet side)
IGNITION WIRES: Call Inboard Online @ (877) 327-7175 and order part numbers 556010A (odd bank) and 556010B (even bank)