Burnt taste comes from too much voltage or not enough
juice getting to the coil.
Since you can't change voltage you need to look at air flow. Reducing the airflow (restricting the holes in the 510 connector). By restricting the air flow you create more vacuum in your tank, more vacuum draws more
juice in to your carto and will eliminate burnt hits.
I love my Smoke DCT Carto. I don't use the dual coil cartos, I replaced them with single coil cartos from IkenVape. I like the fusion series.
If you don't want to add an airflow controller to your set up then you will need to occasionally take a few long pulls on your drip tip without hitting the fire button, this will help keep the cargo full of juice.
If you are using the dual coil cartos you might want to try replacing them with single coil. Duals have the second coil much higher in the carto meaning you need to really makes sure the carto stays wet.