what are you guys using?

[marzac2]

Check in to the Tekno kits (www.teknorc.com) if you are going to be serious about racing it.

30 minutes is, sorry to say too long to safely go for unless you do a battery change. This is not to say it's impossible. It just is a risk for damaging your LiPo battery. You could load on a HUGE pack, but the weight will be too compromising for a buggy to handle in a few ways.

If they are truly running 30 minute mains, I would just do a battery change at 15 minutes in. This will take you about 30 seconds if your pit guy rocks it. This will still be equivalent to the time the nitro guys spend in the pits for multiple fuel stops.

Try 4-6S (4-6 cells)on the batteries. And 1P is all that you need.
6S is best to keep temperatures down. I run 6S always and temperatures of my equipment is consistently lower than others running 4S set-ups. However you must MATCH the motor to the battery you chose. Meaning that if you decide to go with 6S, then you need to get a motor with appropriate KV. For more info on this, check out Tekno's site.