I have 2 of the older HFi12D4 in one box and two of the HFX12D4 in another, both in parallel, so they took same exact power and the Hfi burned up at around 250W RMS (1000 divide by 4) while these remained unaffected.

They sound great, and even though the HFi12D4 looked prettier with the chrome on the edge, and the nice pressure terminals. This one is better because this HFX12D4 actually outperforms them very slightly AND take more power so they won't blow on you at higher watts!

The HFX12D4 are supposed to replace those HFi12D4 anyway.

These woofers are a good alternative to the expensive competition woofers because they SOUND good and they are LIGHTER so the weight won't drag your car down, especially if you have a sporty car you want to keep weight at a minimal.

They're not as loud as the loudest, but they are great for lower power setups as they sound deep.

I would say they are as loud as any woofers around $100 and below price range, and have a nice bassy hit to them.