daloudin Your WinISD results aren't what they should be. At 2.7ft3 tuned at 22hz is not what that sub was intended for. Why not 2.7ft3 tuned at 30hz like it says on partsexpress?
The results are what they are... they are based on mathematical analysis of the T/S specs and 2.7 at 22 is a full on SQ alignment typically used in creating speakers for use in the home - this is where WinISD defaults to when you first start a new alignment. 2.7 at 30 is a nod to the cabin gain and increasing the output above tuning to match the extra cabin gain. There's a mathematical point at which any alignment gives you the best compromise between output and low frequency extension. When pursuing SQ you want the slowest and shallowest rolloff possible as frequency descends. The alignment that has the slowest rolloff is Infinite Baffle, then sealed and then ported, the rate at which a ported box rolls off depends on the relationship between the box size and the tuning point. For the best SQ this usually means a much lower tuning point. When pursuing SPL or "Burp Boxes" then the tuning point is tailored to the driver, the box and the vehicle to maximize the gain at the expense of any output above or below the tuning point. The advantage that putting a sub in a car gives you is the cabin gain that increases the output below the frequency that coincides with the maximum dimension of the anechoic space. For your car that's around 70-80Hz so we'll use 80 to calculate cabin gain and since it's a smaller cabin and you are going ported we'll limit the lower end gain to 20Hz since you'll need an infrasonic filter at that point to prevent over-excursion in a ported enclosure.
Back to your specifics - you have 1200 Watts at 1 Ohm or 800 Watts at 2 Ohms or 400 Watts at 4 Ohms and while you can use the Dayton HO15-4 at 400 Watts we will be looking at mostly DVC 2 Ohm Subs to give you the 1 Ohm load you need to maximize your amplifier.
At 1,200 Watts the IDMax is slightly louder overall but the Brahma is neck and neck and based on tuning alignment you could make either one louder at certain frequencies. The IDMax is a little less peaky for better SQ though...
The white trace is your TC Sounds 7 cuft at 20 Hz and 1,000 Watts modeled in to your car (not that you would but just for reference) and at 1,200 Watts the IDMax most closely resembles the curve of that Subwoofer model, the IDMax and Brahma are on 1,200 Watts and the Dayton HO is at 400 Watts, the Pink is the SQL12 on 1,200 Watts and then the Orange is the SQL12 in a SQ Ported box on 6,000 Watts:
So all of that to say that the SQL12D2 will work fine and is the equal of the IDMax at 1,200 Watts but whereas the IDMax is at xmax on 1,200 Watts, the SQL12 can handle 5x more power for when you get ready to up your amplifier game but keep in mind that all that extra power is only going to net you about +5dB but that's almost 4x as loud.
And here's the nexus of modeling and the limit of what WinISD will let me do in one run.. it starts getting really flaky and won't let you make changes at this point but this goes to show what you can do with one woofer - these are all the SQL12: the Yellow is that best SQ alignment
The Reds are all 1.358 cuft at different frequencies.
Greens are all 1.8 cuft at the same tuning points.
Pinks are all 2.3 cuft at the same tuning points.
Teal are all 3.3 cuft at the same tuning points.
The point being that you can make it look any way you want and easily change the output by +/- 6dB ...
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