i can only speak for the maf forward.
i had one of the first models they made (it was a little smaller than the current model).
on my 01 it probably made 20hp+ (w/rotated maf) this was due to it leaning A/F ratio car made 245hp/295tq with densecharger & pullies.
now on my 02 it was not noticeable but of all the CAI's i would take the densecharger over all others due to cost, cooler & customer service.
i had my densecharger for about 2years & it broke partially due to my error. i called them up to buy a replacement section & they sent it to me for free (even shipping).
they got my business when ready to mod wifes 03 vert.