Definitely need carb heat above 5000ft and mixture all the way forward (which is wrong). No problems for me when I do this but also run in full coarse pitch. May need to throttle back to 2.5 boost but smooth flight is no problem.

I posted this link over at ATAG but will put it in here. It's worth a careful read but here is a paragraph that I think is very relevent if u haven't got the mixture orientation correct in CloD

http://flighttraining.aopa.org/stude...l/mixture.html

"Excessive leaning at cruise power above 75-percent power will invite engine damage from overheated valves and incur the possibility of detonation. The probability of damage from over-leaning decreases rapidly as cruise power is reduced from 75 percent. For example, there is considerably less, if even any, possibility of engine damage from over-lean mixtures at 50-percent power. However, an over-lean mixture can foul spark plugs and combustion chambers because of cylinder misfiring.

Many older engines are equipped with non-alloy steel exhaust valves. During normal cruise power (approximately 50 percent to 75 percent) the exhaust valve will become glowing hot during the period that it is open and exposed to the hot gases leaving the cylinder. If the mixture is lean enough to create an oxidizing atmosphere, the exhaust valves usually will be damaged. (An oxidizing atmosphere is always present in lean mixtures.)"

This may be why u are getting rough performance Ivank if your mix levers are all the way back and u are using more than 75% power and/or climbing.

I see where you are coming from Torian but given these things were meant to be AUTO RICH and AUTO LEAN with documented Boost limits for the AUTO LEAN setting rough running (assuming limits are observed) should not be an issue.

Agreed but "meant to be" and what what we have been lumbered with in CloD are very different. Unfortunately we have to learn to manage the engines in this sim in ways that weren't necessary in real life.
And in the case of Brit fighters, with less performance than they actually had.