If you've got a dual coil at .13 I'm guessing you've either not got many wraps or you're using a pretty thick kanthal. I'd go with the latter as you mention it has a noticeable ramp up if you drop the watts.
You've two options.
One is to, if possible, set up a pre heat on your mod. This will give you a punch anything from 10-30 % more than the displayed wattage for x amount of time then drop to whatever wattage you've set. Handy when you've got big bastard coils that need a bit of help to get them going. I'm using it on a Maxo setup at the minute but not all mods have it. What've you got?
The second option is ditch the kanthal in favour of stainless steel, nichrome or a blended wire. Kanthal has a long ramp up time when the gauge starts getting thick and also takes a long time to cool. So if you've left your Goon for a few minutes and have two toots in quick succession toot one may be lovely, but toot two a few seconds later will be like ingesting Lava because those fat kanthal coils are still very hot. SS and Ni80/60 heat and cool much quicker than kanthal.
As an example I've got a few Goons, the one I have at the minute has a 22g 60/40 Flatwire build in it that comes in at .11, and I'm running it at 140w. It's warm but not hot, and the airflow is wide open.
But the crucial part is that it's a blended wire- 20 seconds after firing it it's cooled down.