Its pretty hefty at 4.4 megs due to the custom sound and textures but the explorable terrain is huge and detailed so I think its worth your time and hd space, and btw its very light in the model/vertice dept. so no lag worries there.
from the read me txt.
"SBM Monster Cross" is modeled after a real mx park located in the hills here in Orange CA. lap times are around 2 minutes and the best sets are 1500-1600 mm pro to get the proper lift.
"SBM Speedway" is just a flat oval for some power slidin fun. good lap times are 17 seconds.
"SBM Gear Jammer" is a helter skelterish rough ride which should challenge the best drivers skills. good laps are 1:30 and under.
"SBM Rally" is a 6 minute stroll over the Saddleback terrain, and if you like to explore this is the track to do so on it has more roads and places to 4 wheel than the others. lastly the map is ugly because it overlaps the terrain grid (several times) but there should be enough signs in place so you can leave it off and not get lost
there's more info in the read me...