Just some general information and thoughts:
Kanger coils don't have the best quality control, so you may have gotten some bad coils, or some coils that are advertised as "similar to Kanger coils". It's not all that uncommon to get a few bad coils in any batch of coils from Kanger. YMMV.
How many cigarettes did you smoke a day? What nicotine strength are you currently using in your e-liquid? The nicotine strength of e-liquid should be comparable to the number of cigarettes you smoked. Nicotine is responsible for the "throat hit", or harshness, in vapor. Too high of a nic level will result in a too harsh vapor.
For e-liquid, the typical nicotine recommendations generally are as follows:
1/2 pack per day or less = 6 mg nicotine
1 ppd = 12 mg
1 1/2 ppd = 18 mg
2 ppd = 24 mg
Harsh vapor can be caused by a higher Pg (propylene glycol) content in the Pg/Vg ratio of e-liquid. Pg contributes to the "throat hit" or harshness, along with nicotine, but not as much.
Some flavors can appear harsh to some vapors, and not to others. Maybe try a different flavor.
What is the resistance of your coils (ohms)? Some folks feel low resistance coils provide too harsh of a vape.
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