Yeah the stock hobbit exhaust was one of the most cruel cruel jokes ever played on a moped.
Seeing as how the proma is the only exhaust out there within the reach of the common man, get it.
This time last year you couldn't get a beat up used proma for 200. They started making them again and they might stop at any time.
Of all the hobbit exhausts I have tried I like the proma or the polini the best. I have heard the leo vince is good and if you have more money than you know what to do with you can get the motomatic.
I am intrigued by those ev pipes dude has. If I had the loot I would buy one just to see what its all about.
You should just get a proma though. Best bang vs. buck factor. 4-7mph more on top plus some increase in the middle.
Do your plug chops though.