Hoczero, I will give my opinion, I have a 14 SGS with 6.5 boom. both 4.3 and 6.5 Boom systems are Bluetooth "receive" only ( not transmit or both). If cost is a concern, you have a few options to GPS, I have a Galaxy Note 4 smartphone, 5.7 inch screen. It will transmit my sirius xm radio app, amazon music app or any stored mp3 file. as well as, incoming calls to my Boom (heads set bluetooth to phone) ring audio out only (no mic on SGS). with all that said, you probably own a smart phone that can give you all the gps features you want and then some and you have the portability of a one device for everything. you can also purchase a usb to av jack cable for other audio options.
ps. google voice command on the phone with a bluetooth headset/mic is a real nice hands free operation for navigation on the fly.
hope this helps.
Dan