What is a boost controller and do I need one?

A boost controller regulates turbo pressure beyond the factory wastegate setting. Manual boost controllers ($50-150) are simple and reliable for mild increases. Electronic controllers ($200-500) allow multiple boost maps, anti-lag settings, and precise pressure targeting. You need one if you've upgraded your turbo, intercooler, or fuel system. Always tune your ECU after changing boost levels — running lean under boost kills engines.