I've been using the silicone caps on an eGo Type B tank cartridge in a Bulli A2-TM. The hard plastic caps will pop off, but sometimes they are stubborn. The silicone caps should last longer and are less prone to leaking. They are also easier to remove.
I also remove the baffle plate in the Type B tanks. I read a tip a while ago to do that to improve flavor. I don't know if it actually does since I've been doing that from the get go and have not done a comparison.
To remove the baffle plate, put a paperclip in the hole of the plate at the mouthpiece end and pop it off. The baffle plate is under the top about 1/2" down, so pop that off the same way. Then replace the top mouthpiece plate and you're good to go. Again, this is for the Type B tanks that I use and I don't know if the Type A tanks are constructed the same way. I'd imagine that they are the same with the difference being that the Type B tanks hold more liquid than the Type A tanks.