You typically don't see much gain, if any, by chopping the tips off these for glow engines. In fact, the lack of backpressure may be a problem for fuel delivery.
Now, on gassers, it is practically a MUST, IMO. In the past month I advised two guys to chop their tips off their bissons on two Evolution 58's, but to tch it before and after, The gain was 200-350 RPM!!!