Just came across this thread. I just got a Master blaster today. It seems to fit quite snugly along top tube (I have a pump peg) and I would like to give it a go without using the velcro security strap. but I have a question. The indent in the handle is quite shallow so doesn't seat fully onto the peg. Seems if I cut it out a bit, I would create more of a hole that would allow the pump to seat more fully onto the peg. Is this a bad idea?
I'm uncertain what you're wanting to cut out but I'll tell you that my MasterBlaster works great on the pump peg without the Velcro at all - no movement whatsoever.