With the Tekin RS and the lastest software, the Speedo will run correctly at 1s voltages, but the servo will feel sluggish as you pass 3-4 minutes race time. Also, your receiver signal and transponder signal will be a little weaker at lower voltages.

I highly recommend a booster (Novak for example) or a receiver battery. The booster circuit connect to the Positive and Negative on the speed control where the battery plugs in, takes that voltage and boosts it to 6.0v. This is the safest and easiest method. The problem with a small LiPo receiver battery is the 7.4v to 8.4v it provides directly to the equipment. Most are not rated over 6v, and sustained high input voltages could eventually kill some servo's or receivers or transponders. If you use a battery, I suggest a small LiPo battery regulator to keep the voltage at 6v. Several companies make then, including Novak, MuchMore, and Losi.