Jakes and high boost?

[Running rough]

Just a thought is exhaust backpresure line functioning, on a North American cm2250 with egr and vgt turbo, this line is on the egr manifold and connects to termastat housing, if you run @m*m^2 and put in a straight manifold make sure to drill and tap and conect this line if your moter is still tuned for a vgt, other wise the ECM has no way of knowing exhaust backpresure and will keep turbo nozzle ring in max boost which could overboost turbo and cause catastrophic damage to you engine