Rob,

For the Carden 260, I will have KS Tuned pipes with a three bladed prop, so I am confident that bird will meet the sound limits .

I also have a 2.6 Composite Arf Extra which will run a three bladed prop and slimline mufflers. This plane should meet the sound test with the three bladed prop, atleast I hope it will.

I was just surprised to see the actual ground sound test in the judging guide. The wording in the judging guide gave me the impression the sound test was required but I was getting the impression they were rarely done