Now that the 120's have arrived in the States, I've seen alot of good info on this plane, but can't find what I'm looking for about engine/muffler mounting issues.

I've got a Saito 150. The stock muffler connects to the engine with a 45-degree angle threaded pipe. The plans call for a 1/16 to 1/8 inch clearance between my spinner backplate and the cowl. To make this happen, the muffler is up hard against the bottom edge of the firewall.

1. Should I go with it as is, and maybe carve a little channel in the bottom of the firewall to let the muffler clear?
2. Should I go with a Pitts-style muffler? Will this clear the firewall?
3. I ordered a MACS muffler extension. This has a 90 degree bend off the engine, then 9 inches of flex steel tubing, then I can connect my muffler to the end of this. He said I can put all the turns I want into the tubing, but this will still put the muffler well up under the plane. If this is the way to go, how can I secure the muffler to the airplane to keep it from flopping around.

I know this engine works great on this plane. I'd like to hear how others have made it all go together.

Thanks for the help.

B-ski

I'm hoping somebody can share their knowledge about this setup.

I am interested also as I have the same setup coming
Jeff

I want to buy a new electric Glider ARF and would like to know which one is the most highly recommended. at least a 2 meter

I have built 6 of these, I also have the same engine you have. The best way to me is to mount the engine inverted. The saitos run fine inverted. This way engine sits in the propwash, and you have clean cowl on the sides. If you add a perry pump to the firewall the engine runs better. Also your tank is above the carb. I have used this set up on my first DP ultiy.

I just finished with that problem myself. I mounted a Saito 1.80 but would need to cut into the firewall to use the stock muffler so I bought a slimline #4006 pitts style muffler that fits beautifully. The exhaust pipes angle back a bit and drop down just enough. I did need to cut the bottom of the cowl so I could get the cowl on though it doesnt hurt it's strength at all. All in all it looks great!
Slimline has a 4006U which is made for the Goldberg Ultimate and has a 70 degree swept back on the exhaust pipes and will also work. I talked to Slimline and someday they will build a muffler specific to the DP Ultimate but I'm not sure they need to.
Good luck!