choosing the right amplifier

Hey everyone!

I bought  2 x Kenwood 12" KFC-W3013 as shown in this link http://www.caraudiocentre.co.uk/product_m-kenwood-kfc-w3013_p-27137.htm. 400W RMS each so I assume I need an amp that can give 800W RMS at 2 ohms as I'm wiring them in parrallel.

I had them installed in this In Phase double 12" sealed enclosure  http://www.caraudiocentre.co.uk/product_m-in-phase-bx212s_p-20693.htm. There is no divider in this box, both subwoofers are sharing the same airspace. Although it was playing bass accurately, it wasn't as loud as I wanted it to be and so I put them in my old Vibe twin ported enclosure as shown in this link http://www.parkmyauto.co.uk/vibe-cbr12-twin-evo-active-ported---3200w-sub--enclosure-295-p.asp. This enclosure also has no divider but has 2 ports. I understand this enclosure is tuned to different subwoofers so should I put them back in the sealed or do you think I can leave them in this box because they sound louder? I have turned the subsonic filter setting up.

I have been running my subwoofers off a Fusion fp-9001D Powerplant monoblock amp which I acquired a few years ago as shown in this link http://www.kandtsales.com/shop/product_page.php?parent_top=Electronics&parent_mid=Mobile&parent_low=Amplifiers&prod_id=152. Apparently it does 450W RMS at 4 ohms and 850W RMS at 2 ohms, these are for 14.4Volts. I think it was 780W RMS at 12V for 2 ohms. Is there any way I can test the true RMS this amp is putting out? The bass is loud sometimes, it plays punchy bass notes well but when it is required to play long bass notes, the subs just dont flex like they do in the videos on youtube. They seem very lazy so I thought they might be being starved of power? If I disconnect one subwoofer from the amp and power only the other subwoofer, it seems to move A LOT more (like how they should) but obviosly doesnt play as loud as the enclosure is too big for one subwoofer.

If the above symptoms above point to low RMS being supplied by the amp and after confirming this by testing, could someone please assist me in choosing a suitable amp from this website as they are local to me? http://www.caraudiocentre.co.uk/

Would it be a good idea to go for 1000W RMS at 2 ohms?

Thanks in advance for the help and sorry for the long explanation!

In what way are you dissatisfied with the setup? poor sound quality? poor SPL?

What are you trying to achieve/fix?