I recently got a GPSS, and I put an SV26 gas engine on it. Spinning an 18x8 Master Airscrew classic at 7100 restrained. I love the way it flies, and it lands like a dream. It's the easiest plane to fly that I have ever owned. I hope they never discontinue this plane...
By the way, with the SV26, it balanced perfectly, and flys for penny's...