i just had the 791xv installed and i am finding the range to be a little less than what i need, i read on here that all i need from the 5900 for the extended range is the remote/antenna/brain and that all the wiring for my current 791xv will plug into the new brain etc. Now first off is that absolutely true? i dont want to buy this and find out that it wont work... and also is it worth it?