better to air on the conservative side
The 2530's should be pretty responsive with 3.1L, take a look at N1GTR's dyno sheets with the GT-RS setup for an idea as to how it would spool up with the larger turbos, as for 400hp with a fat torque curve look at AL's setup (although he has an RB25 head and single turbo it gives you an good idea of what the GT-SS turbos would be like on yours).