2 inch is the biggest Mopar header we have in the dyno room. The headers that fit the chassis are bigger, I think they are 2.25 but they don't fit the dyno. The dyno session is mostly used for confirming the engine is good to go as well as dialing in the EFI tune.

I'm not sure on hp so it will be interesting. I pushed my old 514 with EZ heads up past 900 hp a few times and it had some of the same parts. We used the 2 inch dyno headers for those pulls as well as the same intake and throttle body combo. My heads were a little big smaller than these heads and of course I was giving up almost 60 inches to this combo. The 280/296 camshaft is way different than anything I ran. Most of my testing was with a single pattern cam or a very small split of 4 degrees. I never ran anything with 16 degrees split like this one has. I expect this engine to make more than 900 hp but who knows, the cam and the headers might not get along well enough for that to happen.