The usual items to get when going to a bigger turbo are bigger (often STi) injectors, upgraded fuel pump, larger intercooler to minimize pressure drop, uppipe if you don't already have one, a turbo back exhaust to minimize backpressure with a good design bellmouth or divorced wastegate pipe on the downpipe. Upgraded engine management is needed to get the most out of this combination. Cobb Tuning and Vishnu Performance have Stage kits that spell out what the most commonly used components are. A VF30 IHI turbo is a popular upgrade, although there are even bigger turbos that put out a lot more power at the expense of some street driveability.

Don't forget about suspension and brake upgrades to go along with the increased power.

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