Sadly, 90% of the one’s you will find WON’T fit your bike. The typically don’t clear a “fatty”(wide 7” rear wheel). They almost always end up hitting your wheel. If they don’t hit your wheel then the hanger bracket doesn’t line up. Here is some keywords to search for ones that most likely will fit. This search is catered towards 150cc engines. The 50cc sadly doesn’t have any aftermarket selection. So, again 150cc riders search, “gy6 yoshi”, “gy6 hotlap”. Those are your 2 biggest exhaust options. You can also search on facebook for “Savage Custom Exhaust”. He makes quality custom exhaust for bikes. Before you post in the group asking “does this fit”. No, it doesn’t so don’t bother. You will notice yoshi and hotlap along with save custom exhaust all are made to clear a fatty. It sucks, but it’s part of the game.
As for TRIKES, so far yoshi and hotlap fit fine, savage custom exhaust are custom made so be sure to let him know it’s a trike, likely have to take photos and measurements.