RE: Second Radio System???
Sig 4 star--good second plane.
Warbird--Bad second plane
Period
BTW, you should fly that trainer until at least toward the end of the summer before you tackle the four star. Even after you solo, you'll still be learning a lot.
JR 6102--excellent six channel radio that will last you for a long time. Whatever you get, get a computer radio. Don't bother with the analog stuff.