Are you looking to just upgrade your 350 with the Werks engine....or does your buggy need on altogether? If the former, I would keep what you have. Not to dismiss Werks (I've not owned one but have read/heard only positive things about them), but have been impressed with the 350 and unusure how much of a difference you would see. If you are looking at that price-range and want to change, suggest the B5. I've not seen a B2 in person, but have seen quite a few B5's and everyone I spoke with loves them.