Congrats on the new ride. I have a 660 as well. I would say that the only problem with the airbox mod and that it let ANYTHING inside the airbox. I would at least put a screen over the hole. Better yet, a layer of filter material. I assume that since you mentioned nothing about it running lean, that the previous owner rejected the carb. The user dezz is very knowledgeable about this type of stuff. Private message him. He will be happy to help you out.