2.5 cubes @ 33hz is going to be a low end monster, like exaggerated lows. I could see the 2.5cubes since you're short on power, but tune at least 35hz and 38 would be better for daily. The HDC's have no problems playing below box tuning.
I've done a lot of AQ boxes the last 2 years and have tried everything from 35-40Hz and 38Hz is what I build the most.