First off i would like to say HOLY MOTHER OF GOD I've had the avalanche 15" in my car for a couple days now and it is INSANE.

For starters the ava15" is in a 3.5 cube enclosure tuned to 28hz with a flared slot port, custom box made by Chad himself, just a beautiful box, by far the best ported SQ box i've ever seen or heard.

One thing i did notice that i didn't expect is that this sub has ALOT above 60hz in a car, so much that i had to lower my crossover point down to 63hz 36db/oct because there was so much output from 60-100hz that the sub was very localizeable it was playing those frequencies so loud. If the Atlas has alot more top end it must be able to kick hard into the 200hz range lol. The top end reminds me of the Magnum D2 15"
frequency response. But has ALOT MORE LOWEND than the Magnum. When i first purchased the Avalanche i was under the impression that it was really only good between 20-60hz and then would roll off REALLY hard like the XXX and Brahma do. These 2 subs are lifeless above 60hz (in a 15") and just have alot of low end. The avalanche is MUCH more balanced it has enough top end to keep up with the VERY LOUD low end. So gigantic midbass speakers are not REQUIRED like they are with teh Brahma and XXX.

I had it on a Lanzar Opti2000 but this was WAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAY too loud for me i seriously couldn't use 1/3 this amps power at 1ohm, it was ridiculous. A friend of mine has 2 XXX 15" subs running off of a Lanzar HTG2600D which does around 1400w @1ohm but his XXX's are wired to .5ohm which the Opti2000D can drop to with ease, but the Heritage is only stable to 1ohm so i let him borrow my opti and i threw in the Heritage 2600D and this amp really doesn't seem any less powerful than the Opti2000D @1ohm but thats because at 1ohm they have about the same power, its only at .5ohm the opti gives you an extra 500w but the HTG2600D is regulated so that it won't give you any more at .5ohm and isn't recommended anyway.
I LOVE these amps! They are EXTREMELY tightly regulated so you get max power with 12v as you do at 14v which is awesome.

All i know is that my setup is nearly as loud as his dual XXX 15's with the nearly the same power. So this sub is EXTREMELY efficient. I cannot even imagine how efficient the ATLAS is.

For SQ WOW, this is by far my favorite sub out of any 15" i have ever owned. Its low end is just as accurate as the Brahma, but has MUCH more top end. There are points where the subwoofer SHOULD be forcefull in upper frequencies and attack where the Brahma just doesn't respond to but the Avalanche is just there ALL The time. It is extremely tight, i wasn't expecting this at all! i expected similar performance as the XXX but man was i wrong. The avalanche has as good if not better low end than the XXX which is just sick amounts of bass under 40hz, but has at least 2-3 times the upper bass as the XXX.

If you want an EXTREMELY loud setup that will keep up with some of the best SQ subs out there this is your sub. All you need is a regulated 1000W amp and a well made ported enclosure tuned between 25-30hz and you will be AMAZED.

At first with the Opti i really gave the sub everything this amp had and it reallly handled it without any hint of it being too much but its just WAY WAY too loud for me and i do like alot of bass too. I'm really shocked how powerful Lanzar amps are considering their price, these are some of the most powerful amps i've ever owned for music. And i've used a 2000X, Orion 2500D, Viper 2500D, Concept 2400A, Eclipse 2000w, Memphis 1500D and a few others. For burps these amps are probably more powerful but for music the regulated power supplies in the lanzars keep the power to your subs no matter what voltage you're at. I think the Orion and viper might be regulated too but didn't seem anymore powerful than the lanzars for music. The HTG2600D seriously puts a Hifoncis BX1500D to shame as far as power.

In a 2002 Nissan altima (trunk car) i know i'm easily doing low 140's on a new TL and this is an SQ box!

Well anyway i'll add more later but i'm just not in the mood to do a long detailed review