originals will fail too. My mate drives a calais. Original spoiler. Already can see it start to wear out. Friend has an integra with a replica kit. Not quite sure the exact year (possibly late 90s as im not familiar with that model), replica kit looks good as new. So it just depends on where the kit was made. Not all replica kits will fail.
So far i have front grille and spoiler as replicas. grille ive had for about 1 year. Still looks the mint. Spoiler only a few months. So maybe ill see if its any good in 3+ years time.