Ha Player, there is always going to lot of therioes out there on this subject , so what you should be asking is, has anyone fitted a 155mm pump to a Blaster with a standard tunnel and it didnt work. That is the only way to get to true indication.
I didnt get caught up on all the pump size verses tunnel shape / volume , i just did it and can report that it 100% works perfect. I would be surprised if someone writes that they had a issue. To fit the pump was easy with a few minor mods. Check out my post on this in Oz forum.