Sub box placement in trunk

I have a JL Audio Prowedge subwoofer in my Ford Taurus trunk.  The sould quality is very good if I have the subwoofer facing the back of my car.  It doesn't seem to sound as good when it is facing the front, even when I fold down the back seats.  What the deal with that?  Many professional installs have subwoofers installed inside the cabin of the car facing the front. 

 I plan on keeping it facing the back of my car.  Should I run the amp out of phase? (switching the positive and negative connections on wires to the sub)  I heard this will result in better sound quality (not as boomy).  Is this true?

Thanks GlassWolf.  I moved my sub to face the back of my trunk again and I left it in phase.  I am happy again with the sound quality.  My username changed because I forgot my password and had to register again.  What are your thoughts on using a capacitor?  Would it help my system.  I only have one amp (PPI 2360) with 360 watts going to my sub.  Would it make a difference?  If so, which one would you buy?  I like the Moster Cap with the digital display, but it is $220 and I don't think I need a 1 farad cap.  I am thinking a .5 farad cap would do, unless I add another amp.  I found a .5 farad cap (without the digital display) by Monster Cable thorugh Yahoo Shopping for $50.  I would eventually like to add the Boston FS 80's since I have a Ford car and their web page states that a 5x7 speaker has more cone area and will produce more midbass than a 6.5 inch midrage speaker.  They can also handle a lot of power, so I would add another amp to power these.  I really like the sound quality of the Bostons, but I have met many people who have blown them.  A local car auido shop says that they have had the opposite experience, they said they used to have problems with the MB Quart speakers, so they stopped carrying them.  I disagree, a friend of mine had a nice set ($350) of MB Quart separates installed in his car and I was blown away with those speakers.  He never had a problem with them.

  I agree with you regarding lowering the crossover range of my sub to make it sound less boomy.  I have it higher than it should be (around 105) because my crappy factory speakers cannot produce any midbass.  For anyone wondering about the quality of factory speakers, you can buy the crappy factory spearkers with cheap paper cones and foam surrounds at PartsExpress for around $5 each.  The auto manufcaturers definitely aren't spending much in improving the audio systems unless you purchase their high end system, which costs way too much.  You could buy your own aftermarket system for the same price that would sound much better.