Yes, you will need a bass restoration or a self-calibration unit if your factory headunit cuts off bass at a certain volume. However, some DSP amps may allow a manual calibration adjustment using two pre-amp/output channels that are rerouted to the input channels.
NO
This is not enough info.
Ill explain
There are 2 types of bass restoration.
Its crucial to know what type you will need and want if any at all.
Your radio may have a decent output that has a full range of sound. In that case you might not need to restore anything.
The Epicenter makes new bass notes that were not there. This is mostly used for hard rock and music that has very little bass.
Then there is a Bass eq wich is the accubass feature some have mentioned. This accubass feature just increases the bass output by several db depending on what you set the db too.if your radio has a lack of bass then this device may boost the bass enough to give you the sound you want but it wont create bass from nothing if your radio has no bass ( crossoved over due to Bose amps etc). Most amps have one of these bass eq features. Most amps like kicker and Fosgate have a switch that is called " kick eq, or punch eq which boost the bass at 45hz to around 12db. Audiocontrol just renamed this to accubass and allows you to have just a little more tuning.
As for your factory unit. Most of these factory radios like Bose and other big name brand units do have out board amplifiers under your seats or dash that do have several amplifier channels wich are set to play at specific frequencies. This causes a huge problem when trying to replace and upgrade your factory radio or amplifier because you cant just put a LOC on these type of factory systems and you cant just swap teh factory radio because it controls all of dash board functions of the car!.On most of the high end pricey factory radio unitsl you will get either bass, mids or highs and usually not a full range output becuase the outputs are crossoved over and separated to send specific frequnecies to specific speakers. . The biggest problem is YOU WILL NOT KNOW the capabilities of your factory radio outputs unless you have some sort of gixmo that tells you.
The absolute cheapest device that will tell you and then will fix these problems and allow you to connect to a new amplifier is a Kicker KeyLock Smart LOC. Several other companies make something like it but the kicker seems to be the cheapest but does work really good. Just pray you dont have a system that has 10 speakers and all of them have different speaker frequencies then you will need to spend many hundreds to blend them all back togther in a special expensive devce. You could also just go on the internet, do a search on your vehichle on forums an dtry to find out if your factory radio puts out a decently flat frequency response. If it does, then its most likely just a basic factory radio with no bells and whistles and isnt some Bose setup. In thats the case then you can literally just take the 2 rear speaker wires, connect them to an amp like a Kicker KX series and push a button on the amp to switch to a high level speaker input to the RCS's. Blamo. you have good sound..
If youre factory radio has what is called a Loudness Eq, which changes the eq curve as you increase the volume, then you will need a JL Audio Fix 86 or similar device with a special remote volume knob. The knob will be the main volume you use because the factory radio volume will be set and left alone after you calibrated and programmed the JL Audio device to fix the output of the radio and erase the EQ curve. This curve basically changes the way the audio sounds as the vilome increases requiring you to use a separet volume knob and setup as desribe with the fix 86. Just look up what a Loudness EQ curve is, see if you need to fix that and go from there.. Good luck
