Is there an aftermarket exhaust for this bike?

I don't know the answer. The pilot jet can influence the air/fuel up to around a quarter throttle and depending on the carb type there is generally a fairly wide overlap in the change from each carb stage to the next.
An aftermarket exhaust and air cleaner wouldn't usually affect the fuelling at low rpm/small throttle openings and mostly has little effect until the midrange is reached.

Aftermarket exhausts are often famously less efficient in the midrange than OE exhausts and so a richer mixture is sometimes the last thing needed.
Successful carb tuning/rejetting needs a lot of experience - it is almost witchcraft so if the bike isn't running right and the carb is clean, my advice is take it to a guy with the experience.

There is always a danger in tuning an engine without the right expertise behind it.The first thing you need to consider when replacing a motorcycle exhaust system is its design. It has to fit and attach to your motorcycle properly and easily. It is not supposed to exceed the capabilities of the previous stock exhaust system. The aftermarket system should also suit the bike's physical and technical specifications. If you need any more advice you can visit Motorcycle Exhausts and talk to the experts.

Possibly carb needs rejetting after aftermarket exhaust was installed

Is it a misfire or a popping out if the exhaust?

If its a popping from the exhaust was an aftermarket slip on or full system installed?
A popping exhaust would happen when there are leaks in the system.

If its under warrenty then you should have it checked by the dealer.

Check for intake leaks and exhaust leaks, this is the most common problem on these bikes. If you have aftermarket pipes the "popping" will be more distinct. Put on some gloves and cover the exhaust outlets and listen for a hissing from the pipes and around the cylinders.
Good luck, i hope this helps.

Is the bike backfiring from the exhaust or the carburetor? Does the bike have stock or aftermarket exhaust?
D.

Motorcycles come standard with double wall pipes. The inner pipe turns blue and the outer chrome pipe stays nice. In a stock exhaust system you rarely get blued pipes. Unless, you put on your choke, start your bike, answer the phone, and forget your bike is running (or you start driving and just forget to turn off your choke.). Then you will blue your double wall pipe. Bluing is generally caused by too rich of a mixture or fuel burning in the exhaust pipe. If you put on an aftermarket pipe(usually single wall construction) and did not coat the inside of the muffler pipe, the pipe will generally blue the first time you drive the cycle. An old dealer trick is to replace blued aftermarket pipes with new aftermarket pipes (makes the bike look great on the showroom floor). Again if they don't coat the inside of the pipe with exhaust paint or a special coatings usually about $35 the pipes will blue before the customer gets home. If the bluing is mild you could try a product called" Blue Away"that might help, but should not be used regularly as it takes off a little bit of the chrome each time.

If you're talking about the muffler bracket back near the swingarm, these brackets are not that expensive and are available from either a dealer or aftermarket. V-Twin carries aftermarket parts for your bike. You can find the parts and order them online. I have no idea as to where you could get dimensions for the standard bracket.

wait rivits? what? those kinda hold the exhaust together last I checked. The REAL way to get more performance is to either get a faster bike or buy an aftermarket exhaust. And get it tuned to match. And get good tires. And make sure your suspension is up to snuff and setup for your weight and riding style. And then you can change the intake though that could be done with the exhaust. Maybe a quick turn throttle, though don't buy a kit, use a zip tie. Or 2.,,,

must the exhaust be specific to the model is there no way to take an exhaust made for a similar scoot and fit it to the scarabeo? What is your goal? The scooter exhausts offered by Leo Vince and Malossi aren't actual performance systems. People use them because they want to customize the scoot or get more of a growl sound while also passing emission inspections. Most people in the USA never have an emissions inspection on their scooters and are thus free to bolt on any exhaust they choose. If you are looking for performance you need an aftermarket free-flow system like those used for off-road bikes and your only limitation is how loud of an exhaust you are willing to accept. There are plenty of aftermarket exhausts for pit bikes and small dirt bikes that should bolt on to the S100-4T. Personally I would start by looking at mods people have done on the Honda XR70 since it's about the same size engine and uses the same 20mm Keihin carburetor. Of course if you bolt-on an aftemarket free-flow dirt-bike exhaust you will need to replace the existing restrictive airbox with a free-flow K&N unit and either add larger jets to the existing carburetor or switch to the high-flow 20mm PE Keihin or the 24mm Keihin. Either way, the muffler is the easy part it's getting the fuel/air mix right and that's all carburetor work. ,,,