I am currently running a 15" alpha in a 3.5 cu ft box, tuned to 34 hz, 50 sq in of port area. Sounds good, mostly on rap though, and I listen to more rock than anything else. I was wondering if I would get peakier sound by any combination of the following:
Going to a slightly smaller box Less port area Higher tuning
If your sub is sounding too "boomy" to you its probably due to the box being on the rather large side. What happens is you get good low end, like for rap and such and lose out on the mid, to upper bass. A smaller ported enclosure, would help the sub to still remain loud but keep the bass a little tigher, helping with the mid to upper bass. Going sealed will definitely help make the sub more punchier for your rock music, but may quiet it down too much if you've became used to how it sounds now.
Less box volume more hz tuned. Go with your sub specs tuned to 35 hz for rock. 15 inch subs arent meant for rock, dont get me wrong you can get them decent but you would be better off with two 12's tuned at 32hz