Thanks for all the info guys. It sure is a problem. I flew it last summer on a 12 x 5 but she wouldn't hold a hang and would slide back after a few seconds. The engine was very new and maybe not developing as much hp as it could. Later it had a lot of endplay in the crank so I took it back to the shop. They returned it to the importer who fitted it with a new piston and liner (Duh?!!) so I have to run it in all over again! There's a baffle in the silencer which looks really restrictive so maybe the minipipe suggestion would help it out.

The Ripmax display team use the MDS .58 and hover okay but how they get them to run like they do I don't know. Must be 25% nitro or something. I have one of these engines but it's a dog and I'd never trust it with anything that can prop hang!

I reckon I'll give the motor another chance and run it in (again!) and use a 12 or 13 x 3 3/4 or 4 and maybe try a minipipe. I'm sure that mickey mouse baffle is responsible for lots of lost power. If you take it out it's too noisy and the carburation goes weird.

If that doesn't fix it I'll try the Siato .72 or .91 which sounds good cos I'll only have to change the mount as the weight is roughly the same. And if that doesn't work I'll saw an inch or two off the nose and give it a OS 91. (which I wish I'd done in the first place!)

Can anyone recommend a minipipe?