I personally have the flatline and I don't think its the best woofer on earth. When I didn't know crap about car audio (when I bought it) I thought it was the shit. The woofer gets really loud and sounds really good doing it especially when wired at 4 ohms. But when it starts getting about 1200 watts on it or so it starts to have a little distortion. Anyways up to about 1100 or so it is pretty loud and great sounding. I hit 139.9 db with mine on 2500xxk. It wouldn't be my first choice of subwoofer knowing what I know now, I could take the money to be spent on it and buy 4 very cheap tens and build a box and get a lot louder..... Arc Audio they are a pretty good brand, I stand by their product.