Spoke to a couple of builders this morning, recommended Tomeis or Cosworths if you can afford them as they are better at higher levels of boost and have improved on the subaru design. Only reason they go back to oems is to keep costs down... going tomeis or cosworths adds another 300 over the cost of the subaru gasket kit...

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06 STi: 337hp @23psi on E85...
06 STi: 309hp @22psi on 98ron...