Help, Got no service does sprint nav still work?

[brol1k]

Hey there PPCGeeks, I am from new york city and I am planning a trip in 2 weeks about 3 hours away from here, The place im going to has no sprint service what so ever, I only get service putting my mogul on roam. My question is being that sprint nav requires data to download maps and being that since i get none where im driving to, is there something I can do to get sprint nav to work? does it work while roaming? b/c if not then im switching to garmin mobile which has the ability to download maps onto our storage cards and all we need is satellite signals to get us where ever.

pls help