What's the clearance between your x-pipe and the heat shielding? And do you have dynos available?
I was going to have a custom set made, but (1) without 'rolling' the x-pipe down, there would be contact with the heat-sheilding, and (2) it would seem that the gain with hi-flow or straight removal of the second cats wouldn't be worth the expense given the main cats are still in place.
Anyway, would appreciate more info as it becomes available. Thanks!