I'm looking for feedback on the best approach to take out of the
following options.
Option #1: Purchase one SVS 16-46 @ $479 or one SVS 2-39 @ $429
Option #2: Build homemade system consisting of (2) Dayton 15" Quatro
Series. This speaker shares similar characteristics of the Dayton
Titanic speakers. I plotted it response using WinISD and found its
response to be -5db @ 30hz and -10db @20 hz with a sealed enclosure of
3.3 cu ft.

Option #3: Same as Option #2 but using vented design which according
to WinISD would be flat down to about 24hz and -3db @ 20hz with a box
size of 7 cu ft. tuned to 20.65hz using a port with 14 cm in diameter
and 43.7cm long. How crucial is it to use a flared port and how
difficult is it to find flared ports for such projects.

The parameters of the Dayton 15" Quatro are as follows:
QTS: 0.41 Vas: 186.9 liters Fs: 21hz
Xmax: 10mm (not sure if one way or two way)
Qms: 14 QES: 0.42 SPL: 91.8db 300 watts rms 4ohms Cost: $75.00

Thanks to all,

bsguidry