Need help with buggy conversion

Hey guys,

I'm new to this forum, and I've posted a similar thread on another forum, but haven't gotten much input. It seems that you guys here are hog nuts about electric/brushless.

What got me hooked is my current parking lot truck. I'm running an RC10T4 with a Mamba Max 7700 system on 3S Lipo. I haven't seen anything yet (aside from a couple of on road cars) that can even come close to keeping up.

Anyway, I'm going to convert my Sportwerks Turmoil to brushless. I know that I want to use a Mamba Max controller, so that pretty much limits me to 4S or maybe even 5S Lipo. I think I've settled on running two 2S packs in series. I'm thinking either maxamps 4Ah packs or Apogee limn 3800 packs. Haven't settled on this yet. I might go with more capacity, but I don't think I'll go with anything more than 6Ah. I want to keep the weight down, because I intend to race this buggy against the nitros.

My big question is, which motor? L or XL can? I've been told, by a reliable source, that an XL motor will overheat if I run it without enough of a load on it. So...I've been thinking about a 9 or 10L motor (feigao that is). I'll get the same rpms/v as the 7 or 8XL motors, but with much less current draw. I'm going to be running on a track with the longest straight being 160'. I figure that 40 mph might be a good target speed to shoot for. This should keep me competitive with the nitros with the hottest engines.

Oh, am I correct in understanding that I want to keep my motor in the neighborhood of 35,000 rpms at full throttle on my power source? This is what lead me to the choice of either the 9 or 10L.

I'd appreciate any advise.

Thanks.