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I'm designing a 2.5x6 feet banner for my friend's band & I want to make sure I know exactly how to setup my document, specifically what PPI I need the file to be. This is a banner that we will be printing through a third-party printing company & will then be seen by hundreds of people, so it needs to be as high-quality as possible. Do I keep the PPI at the default 300 PPI, or increase it, or decrease it? Thanks for your responses!