blowthrough?

I'm not sure what this means: "or will they sound fine without the blowthrough". Does this mean building a box that just sits in the bed? Taking out the back seats is the cheapest and least invasive way to go about this. The next option is a blowthru. You can cut out the back of the cab and mount the box to fire into the vehicle. You will be able to use the correct airspace and keep the seats. The box will need to be weather protected somehow, you will need to seal between the bed and the cab and your truck will have a large hole cut in the cab and bed when you go to sell it. The third option is a Bandpass box. I had X12 twelves in a blowthru box that only required a 24" x 16" cut out. The box took the entire bed (chevy 1500 short bed) weighed a ton and just got way loud. I used a camper accordian boot to seal the bed and cab. The bed sat higher than the cab, so there was an offset between the two. The plates were welded back into place when the truck was sold. A ridged bed cap seal out the weather. It took alot of work and skill to complete this, hense $$$ if you have a shop do it. I saw another post with a min. $2,000 for blowthru.

yeah i meant will the subs still sound good in the back of the bed without cuting a hole in the cab and bed, or will it sound like sh**.  Or how big of a difference is there between the two?2001 dakota r/t 1 15"RF HX2

1 1000BD power amp 1 1 farad cap 4 channel amp

Just setting the box in the bed is very ghetto.

...and just setting the box in the bed you won't even HEAR them, unless you have a camper shell with a sliding or removeable window in the front of it, AND your truck has a sliding or removeable window in the back of it. Basically the difference between the two is this: one you will hear, and be able to enjoy what you paid good money for, the other you won't. Your choice, but like audiocableguy says, the blow-thru will DESTROY your resale value. It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."