RE: OS Max .46 SF
It was my understanding that OS didn't copper plate prior to the ABL process. I could be wrong on this.
If you went back to the old RC Online, which imploded due to poor software, there were threads miles long on peeling OS .46 SFs & FXs. People were cussing OS left & right. They had to make a change.
As someone has mentioned, there were some fliers who never had a peeling problem. It seemed to me like these were in the minority, although the ones with the problem were naturally the most vocal.
The .91s, both 2 & 4-strokes were ringed engines so they wouldn't have this problem. The .91FX did have a leak, or somethng, with their remote needle valve. They have since replaced the needle with an assembly with one like that on the AX which works very well.