The Magnum .61 four stroke is a stretched .52. Very light and compact.

I just ordered a Top Cap ARF myself and have been wondering what to power it with. The problem is that I have some OS.32SX-H engines, a couple Leo .37-H engines, a Webra .50 GT and a couple of OS .52 four-strokes. Talk about too many choices...

As some have expressed, I tend to like the .32 sized engines on a model such as this, but the .61 Magnum is very tempting.