you can just cut the rear flap down to reduce the effect you're on about..
I know exactly what you mean however.. I don't have a d4, but i get the same effect on my b4 and bj4 when running a full flapped 7 inch wing.
I've about 4 different wings as i belive they are a very useful tuning aid,
full flap,
3/4 flap
1/2 flap
0 flap
Each is very effective through various conditions, somthing you may be interested in trying?
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