Monoblock amp for sub double voice coil and double magnet.

actually i m interested in P2 woofer and amp Rockford fosgate ?

any brand cheapest than rockford or any recommed brand??

I have an RF punch if you're interested. Model b4 P1 i think. Very very loud matched with a 2ch lightning audio.

i want the new set bro

If you just want loud, a lot of brands can do that and cheaper than RF. If you want quality loud, will depend on your budget.
That said, I do not follow SPL development, so you have to wait for a SPL sifu to help you.
In the meantime, you can pm howie to see what he has. Sorry man, for SPL I dun even know which direction to point you to.