I ended up going with the Kenwood DPX300U, and bought from Crutchfield. Considering they included the antenna adapter, wiring adapter, and additional mounting options, I thought it was worth the slight increase in price over Amazon. http://www.crutchfield.com/p_113DPX300U/Kenwood-DPX300U.html?tp=568...

Hey Silver, Thanks for posting this, I am considering doing a similar thing, and so far you are the only thread I have come across. I just got an '04 Vibe as well (only 56k miles :D ), and am planning a HU, new speakers, and 4-channel AMP that will hopefully go under the passenger seat. You answered...