Ok, the problem (or the advantage) of the DBX is that, for the given thuster size, it's heavy as h... sorry, a hot, unpleasant place. So no matter your layout and Engineering, it'll be slow. Which, on the other hand, means that you can load on the heaviest modules and Engineer options without loosing too much.
On the other hand, the oversized FSD slot means that you can plug in a D-ranked FSD and still get a good jumprange for a fighter.
Also, you won't get very good shields - but if you want to have endurance in PvE, you'll need something there.
So, if I wanted to fly a lasered DBX into PvE (which, honestly, I don't), that's something I'd take as a starting point:
https://eddp.co/u/tj2kvbfL
Mass doesn't matter much, so slap on that Military Bulkhead with the beefiest heavy duty engineering you can afford.
The PP needs a small overcharge, or you could priorize down your FSD, but that makes it hard to run when the biowaste hits the Coriolis station
Thrusters - best you can get, i.e. A-rated with grade 5 DD engineering
FSD: an engineered 5D FSD will give you >20 ly jump range, ample for a fighter
Life support A-rated and shielded, the canopy is a weak point
PD: now it gets tricky - this build doesn't put a big weight on thrusters or shields, so instead of the more commonly used charge enhanced engineering, a weapons focussed might also be viable. The latter will avoid the capacity penalty of the charge enhancement. Try what works for you.
Sensors: D rated is good enough, but I prefer lightweight C-rated for a slightly better performance at less weight. B and A rated use too much power for my taste
Fuel tank: doesn't really matter, but if you feel the need to lose some weight, cut it down to a size 3
Shields: you won't have strong shields, no matter what you do, so you might as well settle for low mass, fast recharging bi-weaves.
Guns: here I opted for focussed burst lasers. You won't get the range improvement as from the long range mod, but you will gain an increase in piercing = hull damage. Add special effects to taste - one scramble spectrum is always nice, inertial impact (unique to bursts) is good against hull, although not knowing where they will hit can be a bit distracting (that 3° jitter... pro tip: don't shoot at your target if a larger friendly is behind it...)
Gimballed on a small fighter - learn to do without them, especially for hitscan weapons like the lasers.
Utility: I like to have one (or, in this case, two) point defense turrets on there. Missiles can be nasty otherwise, especially if you can't outrun them. For the rest - the DBX doesn't need heatsinks (unless you want to equip shield cells, which in turn will reduce your endurance once you run out), and gimbals can usually be tanked or evaded, so no chaff (also, endurance...), but a couple of small resistance augmented shield boosters instead.
