Do I need more power

I have two GNX 10 inch 4 ohm subs hooked in parallel to a Rockford 250 M amp rated from the factory at 273 watts at 13.8 volts. My box is custom made to the requirements listed on the subs. They're almost 8 months old now and I've done my best to break them in, but they just don't slam as hard as I expected, any comments.

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if you have the subs wired in parallel, then look for an amp that'll do 350 - 400 x 1 at 2 ohms.

they are rated at 175 or so each -- and right now you're only doing like 120 each.

So ya, i'd say get a little more power....

but also -- dont expect them to slam your vehicle like a hurricane, keep in mind they are an SQ oriented 175 watt sub... dont expect a miracle -- but, having said that, i do think that if you gave them a good 175 - 200 each you'd find they perform a good deal better than they are now -- a few watts go a long way )

suggested amps -- mtx 4244 (bridge it) / optimus 400xl (bridged 215 x 2) / something by soundstream or hifonics would be cheap and effective -- or bump up to a larger rockford class D, they make respectable product.