I honestly don't know which would be louder. I would put my money on the TC Sounds tc3000 being very underated. I'm sure it could handle 1500 plus daily. IMO the TC sounds driver is a better driver. I believe it will sound better and possibly get louder. The x215 is also a great woofer. I don't think you can go wrong with either. I am just partial to the TC.
You could wire them to 4,1,.25 ohms apiece. the two combined could be wire to 8,2,.5,.125, ohms. I would get two 1 ohm stable amps and run a woofer on each. Or one big 2ohm stable amp and wire to that. Like a kicker kx2500.1, or a pair of kx 1200.1s.
Well if the dd3500.2 is 3500watts at 2 ohms then that would be the best option. But you will def need a H/O alternator and extra batteries. and that will cost you around 1000 dollars to upgrade your electrical system. If the amps run at 1 ohm, then go for the 1100d's .
Matt, thanks for the interest in our new subs. The TC-3000 is priced to be incredibly competitive in my opinion. It should rival most subs costing 600-1000 dollars a driver, especially with the new retail prices floating around from one particular unnamed company. We have been an OEM for a very long time and have made drivers for a huge number of both home audio and car audio manufactures. I can assure you our drivers are priced to make the competition... well.. i better not say it. Lets just say not many companies actually make their own drivers. It's a matter of capacity and capital and experience. We have our own custom built magnetizers that can magnetize over 10" wide ferrite and even neodymium. On a full production scale we can make anywhere from 2000 to 5000 drivers pre month and very large companies typically contract with us to have us design and built their speakers. These prices are factory direct so they should be about 50% of what you would pay for a comparable driver from a dealer, and rival even those deals on eBay that come without warranties.
Our own line of subs are new and we have lot of reputation to build, but we have a lot of new products to throw your way yet. I suspect the car audio crowd is going to love the new TC-5200's which would rival drivers exceeding 1500-2000 dollars.
If you have any interest please stop by our forums, and at least say hi or bookmark it.