well, the Ultima has the heritage as well - World Champion 1987/88
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Although I really like Kyosho, I would recommend the B4 to anybody looking for a 2wd buggy. When Gil Losi jr. puts some work into the RB-5 "SP" that will come for sure in the future, things might look very different. The 2WD class will experience the same thing as the 4WD class in the next months or year (s): more than one competitive car. I am quite sure that Hot Bodies and Schumacher would like to make a little money on this market as well.
Another low-budget contender is available as well, the Thunder Tiger Phoenix BX (aka B3), don't forget about it!