ORIGINAL: s. wallace
I will have to pick up another kit just to tuck away, having built the Sun Fli 3, 4, and 5 in last 10 years the 4 definately was my favorite of the bunch. Only mod was dual aileron servos. Both fixed gear, IMHO this is not a plane to bother with retracts.
Built 2 of them, one ultracote covered and powered with several different engines...OS 50SX and OS 60FP come to mind. The 60FP was just right. Photo of this one in my gallery.
The other was silkspan/koverall and dope finish, used an OS 61SF. Looked great but not as nimble as the film covered version. Sold both of them as I lost interest in VRCS type events.
What was it that you liked better about the 4 over the 5? It seems that the 5 was a huge jump forward in modern wing design with it's taper and somewhat high aspect ratio. I am scratch building a 5 right now and it just looks like it will fly phenomenally well. A Rossi 67 is going on it with a full wave pipe. It should have enough power.