ORIGINAL: flyX
You mean it's making a funky loud noise?
If it's that, it's from fluttering from the control surface. Too much air speed
or your control surfaces set up arn't up to par. Gaps in the hinge line, Hinges mis-aligned, flexing control rods.
Rounded control suface TE will also cuase more fluttering.

If it's a new engine, it needs time to break in.
Yes, more torque less rmp usually means more vibrations at lower rpm.
Maybe some of the screws came loose. Either at the mount to firewall or
the screws the holds the engine to the mount.
Try to twist your engine off of the mount to check it. Look for any slight signs of the enigne lifting from the mount.

I generally drill through the plastic enigne mount and use nuts on the bottom.
I also use allen head screws heads becuase using a screw driver I can't get good torque.
By using an allen wrench I can use pliers to grip the allen wrench and apply more torque.

There's also soft mount available.
Kind of like the engine mount on your automobile. If it dosen't have one, It'll make a heck of a racket and the engine
will idle very, very bad.