I don't know much about the Boge carto you speak of, but it seems like 3ohms is way too high of a resistance for an Ego battery. I have heard that the Ego battery comes in around 3.2v, but I don't know that to be sure, so let's estimate 3.7v for the sake of argument. At 3.7v with a 3ohm atty, you are getting 4.56 watts of power (if it really is 3.2v, then you are looking at 3.41 watts). The "sweet spot" seems to be between 8 and 10 watts. Over 10 can be a little hot for some of Ms T's juices. A 3.7v device with a 1.5ohm atty hits 9.13 watts. Even a 5v device with a 3ohm atty would only hit 8.33 watts.
Again, I have not tried the Boge cart, but after I wrote the above, I did a quick look up on it. It does seem some are recommending it for a 5v device. I guess what I am saying here is that you may be underpowering your vape! I use 1.5ohm Joye atties on my Ego, and it works beautifully. I rarely use cartomizers, but I have used some 1.8 ohm cartos that performed very well with any 3.7v (or so) device that I have. The Kahlua and Cream is a pretty thick juice, which I imagine is not going to perform very well at such low power. My recommendation is to get ahold of some LR cartos and give them a shot. I imagine that you would notice a significant difference in every juice you use.
Brandon
Ms T's Bakery