RE: 50 sx
And as a reply to the original question:
The Jett mufflers are plug and play, and give a very nice boost (I don't have a 50SX though)...but i don't see a reason why they shouldn't work on the 50SX. Just prop the engine to run in the rpm band suggested by Jett.
Don't use the black Macs "exhaust diverters"...they do nothing.
A Macs tuned pipe however will give you a nice boost, and you can tune it for the rpm band your looking for. But it is not plug and play, and will need some tinkering to find the correct setup.
Some info regarding your plane and your intentions with it are helpful here.