I have a DD DSP, so Im not familiar with the one you have. DSPs are very powerful and take a lot of time to learn. Sure you can learn everything it does quickly but to get it to come together takes time.
Im not to proud to say I took mine to a pro to get the last 30% out of it, he said I was 70% there. I had it sounding real good but I knew there was more and he got it all. He had a O scope on it and knew his shit.
As for the gains, the DD has a function that you can turn up or down that increases the amps output, which was less then what it had before the DSP. I don't know if your DSP has that feature or not.
Finally, these are my thoughts only. If you have never messed with one you can get it to play pretty good. To get it 100% you have to have some experience with fine tuning.
2009 Road Glide. 16 in Vindikta Wild Cats. Aquatic AV, Stinger 700X4 to MMatts, Audiopipe horns.
6900pros in the lids w/ sspn.4 1000d, tuned with DD Audio DSI-2. S&S 106, lifters, push rods and AC. Drago 2. CycleRama 575. Progressive monotones -1in. 12in. HD adjustable rear shocks. Painted inner fairing. Tuned with TTS. Blacked out!