I have the Passport SRX in my S4. It works very well but they don't make it anymore. I never really understood the importance of knowing where the radar is coming from. If you're on the highway and it goes off, just slow down. Doesn't matter which direction it's coming from!
FWIW, I've used both the Passport 9500 and the V1 for extended periods of time and saw no real difference in responsiveness. They both did the same thing.
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2014 CC R-Line DSG | 2010 S4 Sold | 2010 BMW 135i Retired | 2006 Lotus Exige Sold