4" peak to peak travel under extreme power but meanwhile with a coil that will have thermal issues under those conditions. OSHA and all that fluff really? Blaming the designer only makes them less liable for the failure that will probably occur. But thats understandable because they sell proprietary drop-ins. Why is Kicker so allergic to large quality coils? If you put a 4K rating on a sub I'd be sure to design something that'll possibly endure levels stated.
I'm not a nuthugger of this brand until they get it right.
These subs only handle 3000 watts, for a 12 and 15. A 3" coil is pretty common for that power rating. The 18" handles more power and it has a 4" coil.
I have recently dealt with a lot of different subs. I currently have vehicles with different brands subs. I have JL, Kicker, and NVX. My JL, however, just blew out on me, but it's a 10W3v2. It's pretty old. I have an old Kicker Compvr that still kicking a kicker L7T. Actually, I just sold my last L7T and bought a new one that just arrived today. Of course, you all know I my son is using the NVX.
JL Audio is a fantastic sub. It does exactly what it was designed to do. It is really hard to say any cheaper brand can perform as well. They are some of the cleanest subs out, especially when mated to a JL amp.
The Kickers are also well made. Some of their subs are sloppy, but still slap pretty hard, which is what the common ghetto thumper likes. They are also pretty durable. If you want cleaner sound, there's the Kicker CompQ and Solobaric. I have built a few cars using both, and they are phenomenal subs. I have done the same with the L7's. They push a lot of air and makes it feel like your subs are bigger than they actually are. Shoot, I just remembered that I still have an 10" L7 from 2002 that still works great.
NVX is a really good sub. They sound clean and hit hard. My son has the NVX VCW12v3 with about 1500 watts to it. I would not say it sounds as clean as a CompQ or hits as hard, but for $75 less, it's pretty comparable.
Rockford, they have recently ramped their designs, so they have gotten better. I would put on the same level as Kicker, but some of their higher end subs will be closer to a JL in sound quality.
DS18 would be on the same level as NVX. They make a great sub, but they don't really do anything to stand out. I have had to replace a couple. To me, they feel and look like any other highend Chinese sub.
Pioneer subs are good if you want a cheap good sounding sub. They hit hard, last long, and sound pretty decent for a sub under $100.
I think that is enough of my ranting for now. I was just reading about all the different brands and started thinking about the differences with them. I have been doing this since 1997, and it amazes me on how far we have moved forward in car audio and how far we have gone backwards in car audio.