well, you can use the blue or gold, but they are a very basic system, compared to the ultimate. id be going with the ultimate (which i have, as does at least another member here) as its feature packed. but youll always get the emanage bashers telling you its crap blah blah. but generally they have never used one (which again i have, so i must be wrong) and are going by what others say.
pretty much any piggy-back will work on an M35. just depends on how much you want to spend