I am also running a slash with a ballistic 17.5. Since I dont know how much you know about the slash forgive me if this info is in real basic terms.

First thing I would do if the slash is still stock is run stiffer suspension. I am running 40wt oil in front and 50wt oil in rear. I also moved the rear lower shock mount to the 2 or 3 hole from the tire side of the arm. Then put just enough spacers in the rear to level the arms. I used 1 thickest and 1 mid spacer. In front I use either the smallest spacer or no spacer trying to level the arms. This should be a good starting point.

I also retarded the ballistics static timing to 25* and my ESC is crap but it has
timing adjustents and I put it at 22*. This may or may not work for you since you have a much nicer ESC than mine. The point is I retarded the timing a bit for a little better torque and a little lower temps since my gearing is 83spur 26 pinion. With the 83/26 my temps are 140 for 5min heats, and 160 for 10min heats. Thats on a day with about 80 degree ambiant air.

A bunch of guys I race with have the same motor/ESC combo and they use a boost setting for better top end and is what I will be doing aswell. Sorry I dont know the settings of a tekin to help with that part of the setup.

Here is my 17.5 in action. this is stock class that didnt allow boosting. http://www.youtube.com/watch?v=8yd0_YUlkt0