I would be concerned with the excursion of these subs. With 8.6 mm Xmax and 100 watts, these subs will surpass the voice coil length at just about 40 Hz. See the file:
12w0-4excursion.jpg
You could make sure there's a highpass filter on the amp you power them with. It would need at least a 12 db/octave filter at 30 Hz, or a 24 db/oct filter at 25 Hz to keep the subs healthy. But you might also consider a sealed 3.5 cu ft enclosure on the trunk side of those subs rather than using the full trunk cavity. No filter would be necessary that way. You'd get slightly more SPL.
For more info, read what kfr01 wrote in Guide: Using WinISD
"Determining Excursion Based Limits - i.e., How to Use Your Brain and Not Kill Speakers
Alrighty. All too often I hear, "What the heck, my subwoofer is rated for 500w but I broke it using a 200w amplifier!"
Manufacturers often list THERMAL power limits. These limits are NOT mechanical limits depending on your enclosure. Ported enclosures REDUCE power handling capability. When you use a ported enclosure, EXCURSION, not thermal capabilities, will be the limiting factor in your SPL. This varies based on enclosure and system design. I'll show you this. I'll also show you how important subsonic filters are.
To learn about excursion limits click the arrow next to "SPL" and select "Cone Excursion." Funky graph, right? As frequency drops, cone excursion will increase. For ported enclosures excursion will then decrease when approaching the tuning frequency. Below the tuning frequency excursion will rise rapidly. This should be what you are seeing. As you should see, the 15" driver has plenty of excursion headroom above 20hz when given 200w of power. However, let's increase the power a bit. Try 700 watts. See how the curve now crosses the red line? Your subwoofer would have gone past xmax and would likely be damaged.
Please note the way the curve is FAR above the red line around 15hz or so. This shows the need for subsonic filters on ported enclosures when you have a huge amplifier. If a 15hz note happens to fly through the amplifier when the volume is up, damage is likely. You may even simulate filters with WinISD. Go to the "EQ/Filter" tab of the driver information box and add a highpass butterworth at 20hz. See how the driver is now protected? No more over excursion at 15hz. Flip back to the SPL view. This filter has affected frequency response above 30hz, but only slightly.
Play around with these tools. Try comparing the excursion limited power handling and SPL capabilities of the two drivers. You will quickly see that the 10" driver will meet excursion limits at only 350 watts compared to the 700 of the 15" in our ported enclosures.
This is also useful in making amplifier buying decisions! It would be unwise to buy an amplifier above 300w for this 10" driver in a ported enclosure if you like to push your drivers. You'd very likely push the driver past xmax on a frequent basis and break the driver."
Use this program to help you find the best way to use those JL subs.
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.