Which would you chose?

Adire Brahma 12" mk2
http://www.adireaudio.com/Files/BrahmaOwnersGuide.pdf
OR
AVI SLS-300
http://www.avisound.com/pdf_files/SLS-300-SP.pdf
Both are in the $500.00 CAD

AVI...

Support a great Canadian business, buy AVI ;)

what are your expectations for bass?? Sound quality, or SPL ? how big of a cabinet can be put in your ride?
What does the rest of your system comprise of?
Both are great speakers, question is which will work better for YOUR application?

imo, you would be hard pressed to find a better sounding woofer than the sls300, it is my reference woofer for car audio, having said that, i have never heard the brahma, and no very little about it, so i wont judge. the avi is by no means a spl woofer, if that is what you are looking for you will be very disappointed, but if, stunningly accuaracte well defined bass that will rival some of the finest 12" woofers available is what your after, i would audition the sls300