gaining more volume by adding speakers?

[ncc74656]

i run alpine 6.5 component system in my 2500 dodge ram. the tweets are going and the mids just are not loud enough to cope with my BL18. i intend to upgrade my amp and then i dont know what to do about speakers.

my thought is: i cut some holes and add a second pair of 6.5 alpines, maybe wire them into 2 ohm so i can buy a cheaper amp but still power them. the 4 ohm load would require me to spend 600 vs 300 on an amp. MSRP that is, i was looking at rockfords. now if i wire them into 2 ohm how would i power my tweets? second amp? maybe its easier to buy a larger 4 ohm amp?

i was looking at this for my upgrade amp: http://www.rockfordfosgate.com/products/product_details.aspx?itemid=120386

my current MTX is a 50W per channel so its a but low for what im doing.

i am thinking up upgrading my alpine X tweets to polk audio DXi1001. should i use my alpine cross over for this? they are tiny things that sit in the doors.

another guy mentioned i should look into a processor, i dont know what that really does? is it just an equalizer for my highs? if so i assume that differs from a cross over in that i can adjust exactly what they get HZ wise. however they rae crazy expensive so id rather not go that route if i can.

my DEH 7400 deck requires me to pull bass from teh sub to not max out the speakers and i would like to fix this, perhaps just an external cross over would help?

im looking for guidance and advice. id like to rebuild this system on a budget but i dont want to go with poor parts. let me know please if any of the parts im looking at are sub par.

thanks.