Quote Originally Posted by nepbug View Post
That's a lot of good info. Even with the EJ251 shortside radius, they still flow better than the EJ25D though. IIRC the 251 heads are some of the best flowing subaru heads turbo or NA.

DOHC does leave you more options with changing the cam profiles to suit.

I'll follow this build closely as I am thinking of force feeding an EJ251/252, though I was considering a piston swap.
Stock for stock yes. But if you unshroud the 25D the flow numbers are outstanding. at my old shop we had a bunch of junk heads and we went through a bunch of them developing the best unshrouding formula. The flow numbers on my heads after porting and unshrouding were seriously impressive. Our flowbench guy told me he thinks the 25D is every bit as good as the 257. They just suck from the factory.

Granted this is what our flowbench guy told me, i dont that much about airflow dynamics.