if you really want to port a head, the 2g head can be ported a lot more aggressively than a 1g head. But Stock:Stock the 1g head is fine for 500whp and flows better than the 2g head.

What are you going to do for tuning? If you plan to stick with AFC, I wouldn't go bigger than a 16g. A 20g can be done and has with great results, but you really wont be taking advantage of a bigger turbo without a way adjust/control your timing.

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