I ran one on my OS .46LA/Humongus, and liked it a lot. Wonder if these would be shorter, for lower rpm range? The standard MACS Mufflers need to rev up a bit... 10k+ for the .46. I'd think mufflers for smaller engines would be for higher rpm, and lower for bigger engines. Fuel economy is one good feature.    Steve

What is the weight compared to their Black mufflers? I noticed the outlet is a little bigger on these.

Supposedly, years ago, these mufflers had a notorious reputation for breaking at the flange. Have they corrected that problem?

That looks like a template for the 90" version. I don't think the 82" pipe would look as good on your Shark as that one does. I would have some concern though about how close the outlet is to the leading edge of the wing. That was an issue I had when I tried a black version on an OS 46SF I ran for awhile. 

I don't see a need for the 82 deg. version. There can be interference between muffler and LG on a profile, or muffler and wing on a full fuselage with upright or inverted engine. On mine, I put a slight kink in the stinger, for just a bit more clearance over the wing on the Hugemongoose.

Basically, the high rpm requirement (i.e., small prop) is somewhat of a disadvantage. I'd opt for a Randy Aero machined tube muffler...$39, I think. You'll want to add a "rubber ducky", and ream out the outlet. I added a 6-32 pressure tap to the one I used on the .46LA/Skylark, and muffler pressure. I like it. I've used the Randy Aero muff on the G.51/Mutant Magnum, but didn't get around to pressurizing it yet. Probably soon, tho. There's +/-'s to it, but I tend to like it.  Steve