Pros: Very loud, well built, high Power handling for burps, sounds good on music, handles x2 rms for daily use OK.
Cons: Poor packaging from the factory, no gasket to keep things looking clean.
Overall Opinion: When the boxes came in the mail I almost crapped myself in fear. The single layer of cardboard was beat up really bad, and there was a single thin piece of Styrofoam crushed to tiny pieces under each motor. basically the subs were loose inside the box. Amazingly they were in perfect shape other than a few scratches on the motor which looked like they did not occur in shipping.
They look fantastic, if it wasn't designed to where trash could get into the gap easily I would say they should be reverse mounted. My vehicle is my daily/work/kid hauling vehicle so that wasn't an option.
My enclosure was 15ft net @ 36Hz, though tuning drops a bit in vehicle. I powered them with an American Bass 1000.1 at 4, then .5 ohms once I had my charging system up to par.
Very loud, sounding great on the rock I normally listen to, as well as most rap. By no means top notch SQ, but not shabby at all compared to drivers in this power range. I built a 2nd box - 18ft net @ 32Hz, and I wasn't as happy. I didn't gain much if any low end, but lost a ton of output. #'s wise I would say they were decent- 151 @ 32Hz , 151.6 @ 42Hz legal on 5000 watts total. I never metered after wiring to .5 ohms, but from past experience I would estimate 153ish @ 32Hz give or take.
I wanted to go another direction, but I would probably just get 18s in the future. I see people say this sub will take 10kw all day, but that wasn't my experience. I would probably stick to around 3500-4500 watts for music on these sub, as thermally I didn't think they liked more than that after about 20 or 30 minutes of solid full tilt play. For burps I can see using 10kw or so without issues.
Great daily sub, better for competition imo. I think 18's worked a bit better in my situation so I would give the 7.5-10ft enclosure a lot of thought before buying the 21's. One last thing was the missing gasket- they don't have one for 21s. I didn't like the look as well- not a big deal with as nice as the rest of the sub looks but something else to keep in mind.
diymobileaudio.com is the DIY car audio install forum for automotive quality and spl stereo bass. 12 volt audio installation wholesalers buy amps, subs, double din car audio head unit electronics and ipod blue tooth car alarms at discounted prices