hmm imaging... you close your eyes, and can see the sound stage, you can see the bass off on the left, the drummer in the back of the stage, the vocals in your face, and the lead guitar off to the right.
here's something I found
What is it ?
Basically it is the direction that the sound appears to be coming from on the imaginary stage in front of you, (left, left centre, centre, right centre, right) it also includes the depth and width of the sound to give an impression of distance.
How do i get it to image ?
That is the hard part, there are so many things that can effect the way a vehicle will image,the main aspect is the speaker placement, how far away they are, if they are angled towards the listening position, if there are any objects between the speaker and the listening position and the quality of the speakers used.
One of the first things to do is to try and place the speakers as far forward as possible in the front of the vehicle making sure that they dont interfear with any controls, this is always a good starting point as it can make a lot of difference to the final outcome, try to have an angle on the speakers, as this can also improve the imaging by reducing phasing problems, if the speakers being used have a separate tweeter then this should be placed as close as possible to the mid/woofer, some people place the tweeter in a higher location to raise the image but if the stagging is correct this technique is not as effective.
The tweeter should be angled towards the listening position to make the sound co-exist more with the mid/woofer.
Another important factor is the amount of rear fill, if there is too much then you will never get it to image, because the sound is being wiped out by the back speakers !
Make sure that the subs aren't too loud by turning them down so that you dont notice them, then while listening for the image turn them off, you should notice the difference, this means that it is close to being correct
If you are really keen you could try adding a centre channel, this works a treat if you have an image but it is too wide or it moves drasticaly when you move your head a little bit
Finally if you have tried to do all of this and it still won't image, go out and buy a time alignment processor, because as long as you have tried all of the tricks that i just mentioned and nothing worked this may be your only option.