As for getting knocked off, it won't (trust me I gave it a few really good "tests"). The thing that worried me about the elbow was the it put the filter right up against the HSN. In a really extreme bashing, it might damage the HSN, and that would suck. If I'm not mistaken, the MS for the T-max had an elbow that should have put the filter almost horrizontal, but I'm positive that it wouldn't fit the carb on the 21bb.