You have been given bad information here. Those Tantric subs are nothing special that will require unique parts to perform as though they were new. When you use a motor that big, you pretty much throw in the biggest coil that'll fit, make a stiff suspension, and make sure everything is properly aligned and glue joints are strong. Sure you'll get some TS parameter variance, but the huge motor is just so strong that it will dominate how it performs to the point where slight variances due to different coils (within reason) won't be very dramatic or possibly not noticeable at all.Get yourself some calipers to take some measurements of the gap and pole piece height (or better yet, dimensions of the old coil) and you can begin shopping around for a coil. From there suspension and cone will make even less difference.