Jim, It rolls straight as an arrow and does BIG loops.
It's like an older aerobatic trainer, forgiving and easy to fly.
And it is as fast as some of my old 1970 pattern planes.
I like it, now I would like a bridi pattern plane.
Any one who wants to trade a NIB 60 bridi trainer against Dirty Birdy 60?

Jim, yes the muffler works great turned down, but it's the Coanda effect any how, fast moving air search for a flat cerfice to follow.
But it's alot better then straight backwards.
I've done it to my ST 90 to, alot less cleaning.

Take care.

Joakim