Which Woofer is better and why?

SPL is not the same as sensitivity.... http://www.electronixwarehouse.com/education/glossary/S.htm That will clarify the two for ya.

As Alpine said above, Audiobahn's products are considered of weaker material and fail faster. Most people dislike it(I am one) and some like the product. Really, you can find other names that produce better quality subs like well, it depends on how much money you have to work with and what you want. That'll make it the easiest for suggestions to look at.

I think Audiobahn stretches the truth with sensitivity numbers.

Their Immortal sub's 97db ... please.  Make me gag.

In other words, picking Audiobahn just because of efficiency numbers wouldn't be smart.  Unless, of course, you believe that Audiobahn magically produced a woofer breaking the laws of physics that all other driver manufacturers are bound to.  It is precisely this kind of rating - designed to catch unsuspecting customers - that turns me off to Audiobahn.  You'd think if they actually had quality products they could use the same system as everyone else.  Just something to think about.

Caveat:  The numbers could be correct - for the test that they conduct.  For example, they could be measuring efficiency with the microphone closer to the driver, only over a certain range, or using any number of variable and non-standard ways to conduct their tests.  Subwoofers are much more efficient if only tested over a limited and relatively high frequency band.  i.e.  70-120hz.  If something looks too good to be true, it probably is. 

In any event, it would be foolish to pick Audiobahn simply based on efficiency numbers.

Sensitivity is pretty much meaningless when looking at subwoofers as power handling will be determined by the enclosure.  IMO shooting for a high efficiency in car audio is a mistake.  This is because you have to give up something to achieve this higher efficiency.  You have to either give up low frequency extention, or give up a smaller enclosure size.  Power is cheap so I would much rather have an inefficient sub but have the better response and have it not taking up all of my trunk.

Now as for Audiobahn, they are not testing their subs the same as other manufacturers.  Most ratings are done at 1 watt at 1 meter.  Audiobahn does their testing at half a meter, with 2 watts (2.83 volts on a 4 ohm driver) and in vehicle.  All those things give them that inflated number.  But it is not a good comparison to other speakers as no one else does that.  That's like claiming my car is fastest because it is a 3 second car, but not specifying that the 3 seconds is tested at a few yards and down hill and not an actual 1/4 mile time.

Steven Kephart

Adire Audio

Just animal testing.  DB to them means "Dead Bunny", which happens when bunnies  stare too long at flashy chrome flames.

Steven Kephart

Adire Audio