My own experience after receiving the SVD kit.

There are 2 heads provided but for some reason, in my case, they have a different resistance (2.2 and 4.1).

For the 2.2 head i like to vape at 3.5V and 4W. I've got a nice taste and a lot of vapor.
If i increase either the power or the voltage then the taste is way too strong and tend to burn a bit.

For the 4.1 head i increase the voltage to 4V and it's quite fine.

The 2.2 head is so much better tho. I don't understand yet why they'd have a different resistance but hope to find out.. lol
Also, the taste and vapor levels seem to depend a lot on the liquid you use.

Dekang Mint -> Fair taste / low vapor
Dekang Vanilla -> Fair taste / low vapor
Dekang Cherry -> Strong taste / high vapor (love it)