to get the best soundstage ideally your tweeters need to be as low in the kick wells as possible, and not far from your mids but not far infront, either the same distance or behind the mid, this like bam says will give u a wide soundstage, the ideal point for tweeters and mids is for them firing behind the drivers head about a foot behind, so technically your left door speaker will have a different angle to your right door as your right door is more facing u,
or alternativley use a headunit with time alignment or "correction" to delay the firing of the drivers door speaker so it gives the impresion that the speaker is further away,
hope that makes sense, you will be amazed at the difference in SQ u will achive by having your components on "axis" (technical term for correct position)
Tom