I have a DA150 with two KS mufflers and no matter what I do I can not get the engine to run consistently in the mid range. In normal flight the engine is pretty faultless. On the ground the pick up is awesome but as soon as I go to prop hang or torque roll at 1/3rd the half throttle the engine will not settle down. It either drops RPM or races up as I put a bit of throttle on. I just cant get the model to stay still when upright. Does anybody have any suggestions as I am going a little mad here
Thanks for your time
Regards Al

check out cactus aviation or aircraft international they have a fix
for mid range that works. they are in the usa or check out 3w in germany. there is a new carb 90 degree intake and also a tube to the diafram hole on carb.
I don't know if this is the fix for your problem but it has for other people with mid range problems

Here is how I have resolved mid-range problems, and I now do this on all my gas engines.

I set the low needle so that when you start a cold engine it will not transition as you move the throttle. In other words if you start the engine and immediately give it full throttle fairly fast, (with out warming it up) the engine dies or almost dies. Then after 1 minute of running at about 1/4 throttle you hit the throttle and it should transition fine.

I have my timer set on the transmitter to start at about 7% throttle. When I start the engine cold, I then slowly advance the throttle to about 1/4, watch the timer for 1 minute and then run the engine up.

Now you may already have done this as it is a common way of adjusting the low end. In that case you may have to do the intake and vent tube, but I have never had to do either.

Hope you get it figured out.