I've altered the thrust value from 30000 down to 22000 and it performs better now, meaning not like a rocket.

Remember, "fun" could very well mean "always enough thrust" so I don't blame the devs for setting up this value together with a very low drag component on this plane.

I did some calculations over at Avsim (maybe Mark refers to them, I don't know) and from the pure thrust setting in the config, we are underpowered.
But, as said, nobody knows how the drag is calculated here and everybody surely will have experienced the unnatural high performance of this big bird even on high loads.
I very much join in with HvyEng, the drag component would be the one to look at. But as the thrust change can easily be done by any user, I'd say that a current workaround (unless you need the extra performance) should be based on this value.

So to counteract, an even lower thrust can be recommended.
Fuel Flow therefor rises a bit and gives you lesser range, but as some guys have already tested, range isn't a problem with the default 30000 value. With 22000 it might get closer to real values.

EPR values and even EGT aren't things to watch closely here, they belong to the default FSX engine model and therefor show "some" values, not accurate ones. N1 seems better to roughly estimate power output.
But, hey, talking about a fun product with a very nice price point and great atmosphere here, so enjoy it.