Exhaust manifold crack on ISC350 and effect on power.

John,

That looks like a very recent break-- no "sooting" around it yet.

And, it will affect "all the above".

Exhaust escaping upstream of the turbo will mean the turbo does not turn as fast, so less power.

Probably biggest issue will be substantially less braking HP from the exhaust brake. While the brake tries to hold, say 55 PSI of back pressure, that large a crack will bleed off most of that PSI.