so is dbz kai like a Dragon box remaster

[Kingbrockstar1995]

I know it's a different series but it feels like a Dragon box remaster

[Dragon Ball Ireland]

Nope, Kai was an attempt at bringing the show to HD, the Dragon Boxes were SD and presented the show as it was, an old show from the 80s and 90s. The former also has a softer, sometimes smeary look whereas the latter has a more dated look, although it's more consistent with the original Japanese airings.

[Kingbrockstar1995]

AH thanks it just felt it was

[Robo4900]

I know it's a different series but it feels like a Dragon box remaster

"Dragon Box remaster" is a misnomer. The Dragon Boxes are, themselves, a standard-definition remaster of the original 16mm film negatives (and, in the case of a handful of Namek episodes, and the movies, 35mm film negatives. The OPs/EDs, previews, and possibly also the recaps were also taken from first- or second-generation film rather than the negatives).
Toei had all of the relevant film material transferred in the early 2000s. This was probably done quite cheaply, and with only minimal (if any) colour correction, which results in weird, inconsistent tinting, poor calibration of brightness and contrast, and at least one episode has framing issues resulting from the telecine (scanning equipment) being so poorly aligned that it goes well off the bottom of one film frame and shows the next one (see this strip of film; each frame of something on film is presented in order on a strip like this. Align your scanning equipment wrong, and rather than getting one film frame for each frame you capture, you'll get bits of the next or previous film frame).
Regardless, this early 2000s transfer was used as the basis for some distribution of the series (DB and GT were both given, in this raw form, to Japanese TV stations, and Funimation were sent this master for their presentation of GT. Funi were also seemingly sent at least some of Z, which they used as the basis of one of the Cell era DVD singles in ~2004), but it's most well-known to us fans from Toei having it cleaned up and put onto the "Dragon Box" DVDs.

So, the Dragon Box masters are a standard-definition "remaster" that will always be limited by poor transfering. You can't make it HD, and you can only mitigate its various other flaws (for instance, many fans like to colour correct the picture themselves).

Kai was a separate scan of Toei's film carried out specifically for the production of Kai. The scan was done in HD, and for Kai 1.0 at least, proper colour correction was carried out, and they prepared good 4:3 and good-enough-for-TV-broadcast 16:9 framing.
Kai had a lot more DNR (digital noise reduction) than the Dragon Box, though. The Dragon Box DVDs do have some significant DNR, which causes some motion blurring artefacts, but Kai's main problem is that they applied an aggressive spatial blur, making the whole image very, very soft, almost mitigating the advantages of a HD image (but not completely). The results are still far better than anything you could get from trying to "remaster" the Dragon Box DVDs, though. It's just a shame Kai's transfer only covered the footage they used (as far as we know, at least). If Toei had scanned all their material for Kai, we would have a pretty good HD version of the entire DB+Z+GT series.
But, it seems that Toei's attitude was that by doing Kai, they could "Remaster"/"Refresh" Z in HD, in a far cheaper and potentially more commercially exploitable format than if they did a proper "Remaster" of the entire Z series.