ive had both subs both with 450 watts in the same box. I think the RLP may be a tad tad... tad louder. But the idmax had just alittle more SQ with less of a boomy sound. They both sounded beyond amazing regardless. The IDmax will get much much louder and have teh same SQ if yo give it 1000 watts thou. Rlp wont take 1000 watts for to long. So id go with the idmax. It was in a ported box 2.35 cubes tuned to 32 hz. sounded amazing. And if you go the RLP route. I have a cheap rlp in that box if you wanted it for really cheap.