UPDATE-
ADDED "Official ViPER4Android Audio Effects" TO THE "MODS, KERNELS & PRL INFORMATION".
IF YOU LOVE YOUR AUDIO, I DEFINITELY RECOMMEND GIVING THIS MOD A TRY.
PLEASE MAKE SURE YOU READ THE INFO ON SETTING IT UP. ALSO, WHEN YOU 1ST INSTALL IT YOU WILL BE ASKED WHAT QUALITY YOU WANT, I CHOSE THE BEST. IT DRAINS A LITTLE MORE BATTERY BUT MY MUSIC IS WORTH THE EXTRA DRAIN ON THE BATTERY IMO.
Works nicely, except with the battery mod I have. When I turn the screen off the battery mod puts thigns in sleep mode and turns off the 3g data. This seems to affect viper some how, because when I come back I have to toggle it of, then back on again for it to re-engage itself.
It does work well though. If your on AOSP/CM type roms, I'd HIGHLY recommend this, it's a definite best of the best out there and when I say this I mean it truly works, where as others are hit and miss and mostly don't work. I've used this in TW roms as well, so it works there also.
Only thing I've seen is with the sleep mode.....I think I read on the thread they have that it's a known issue and some have it some do not.
It's really a toss up as to what app is the cause, becasue I used greenpower, which is picky how it works, some times it works other times it does not, while DS Battery defiantly works without issues, so while it worked for greenpower, it doesn't for DS. Kinda a choice to make sorta heh.
I ordered the ZL battery though so I may go back to greenpower and keep viper. I guess it's how DS makes the phone sleep, it does a deep sleep, so I dunno...kinda hard to choose.
Again though this aside, it's a very awesome app, and free as well, and for a eq/booster app it has a nice selection of stuff to set, reverb, room size, enhanced speaker, an eq slider like DSP, it's basically DSP on steroids, it's loaded.
Ok Update:
Other than I'm a total idiot sometimes, viper4android works just fine.
I forgot that one of the solutions or work around was viper installs under user apps directory data/apps so in some cases apps need system access to work correctly, so to resolve this it was as easy as moving the file to system/apps and reboot.
I had this issues once before and totally forgot about moving it to the system/apps folder, so now it's persistent in the system and works as it's spose to. This is even when I have DS Battery set to the most aggressive setting there is disabling ALL apps and doing a COMPLETE slumber, that means apps, outgoing checks, 3g, wifi, anything is put in slumber mode, it's even more aggressive than the aggressive setting which turns on every 2 hrs for 1 min to check thing. I always like controlling things so I set it to ALL OFF mode and check things manually as needed.
Anyways on topic, yes viper4android is THE best solution if you have low volume.
PLEASE KEEP IN IND THAT I AM UNABLE TO TEST 4G IN MY AREA AT THIS TIME SO THE 4G QUESTIONS HAVE TO BE ANSWERED BY THE GUYS WHO HAVE IT. 
