Like many I have been a little disappointed with the forward flight ability of the DR-1. Looking closely at other similar models (hubsan H203) I noticed that the cyclic control servos were reversed compared to the DR-1. Having switched them I will not say empirically that it improves forward flight, once you bump up the rates it definitely improves the feel. Also the limited throw moves when you switch them, left aileron cyclic suffers.
I'm not sure if it's the linkage or the angle, but if you're comfortable taking the whole heli apart it's worth while.
First I would recommend marking the plugs with a sharpie for correct orientation and slot:
The servo plugs will end up switched once you're done.
You're going to take the inner and outer side frames off to get to the servos. The inner may be sharp near the receiver(silver bellow). Once you remove the screws holding the servos in you'll notice they're still stuck in there. They're taped to each other and the frame, the way I got them out was to gently spread the frame and push from the bottom through the holes in the frame to break them free.
Break them free from each other,(short goes on the left, long goes on the right) I never re-taped them in and they seem fine.
Find all the tiny screws and reassemble(make sure the motors didn't eat one).
If you're not comfortable taking the whole heli apart you can do a few thing to balance the heli forward. However it will always want to fly forward slightly.
I you look a early pictures of the DR-1 and similar models, paying attention to the tail fin, you will notice that it has grown fatter. That is because there is a gram of balance weight in there because the tail boom support doesn't come on the DR-1.
It's actually two smaller pieces that fit into pockets on the tail:
They're pretty difficult to remove. Removing one or both will change the balance of the heli.
I'd also play with adding them back on in different places on the heli.
Like under the switch.
The extreme heli side plates will also change the balance of the heli because they weight half as much.
.7g vs. 1.4g which is about the same as one of the tail weights.