i personally recommend a 5s, 5000mah, 25c or 30c pack for this type of setup. it seems to be the best combination of controllable speed and torque. i currently have all my setups (3 truggies) with a Tekno Neu 2200kv 1515 1y and 5s lipo. 4s was a bit too slow for my tastes and 6s is just insane fast and unnecessary. 5s will still give you 45-50mph speeds if you want.
as for pinion i would run a 15,16, or 17t depending on the speed you want. visit the RC calculations page for more info. without factoring tire ballooning a 16t pinion will be about 50mph top speed with 5s on 2200kv Neu according to the calc. this is probably pretty close to what you will see. if thats too fast just gear down to a 14-15t pinion. good luck.
btw, be sure to post pics of your setup. i have been considering getting a STRR and would like to get feedback from someone who has one.
http://www.scriptasylum.com/rc_speed/_top_speed.html