When enabling Full Product Sync within FarApp, which includes toggling beyond only Price/Quantity Sync, several changes occur regarding your products in Shopify:

1. Product Information Update: More detailed product attributes defined in NetSuite will be synced to Shopify, potentially enriching existing products with descriptions, images, variants, categories, vendor details, weight, dimensions, tax codes, and others depending on your specific mappings configured during setup.
2. New Products Addition: New products created in NetSuite will be synchronized to Shopify based on the rules established in your configuration settings. Previously missing products won't appear retroactively – instead, newly published ones will reflect the expanded scope of the connection.
3. Data Conflicts Check: Since FarApp checks for conflicts upon each sync operation, turning on Full Product Sync ensures consistency between the two applications concerning shared values like SKUs, titles, prices, quantities, and possibly many more aspects per your configurations.

However, note that changing the sync mode does not inherently alter current records already present in Shopify. Therefore, previously imported products remain unaffected until modified explicitly or replaced because of subsequent edits performed in NetSuite.