BTW, what da heck does foamies have to do with the GP Spacewalker anyhow?

root, glad you liked the SW. The YS .91 will be perfect for it. Don't take the balancing for granted though. I think you still need to be careful with it. Plan on placing most components (batt, servos, etc.) as far forward as possible. The YS is a bit heavier than most .91 4strokes, but it isn't heavy enough to give you a free reign to put the radio gear where-ever you want. Good luck.