never years of those and thats why I would recommend an exhaust system thats has been tested for years for that price. Theres a lot of good options and different styles. To name a few i would take a look at supertrapp, bassani, vance & hines, thunderheader(shitty bracket but best sounding pipe in the market and good power too).

It depends what kind of bike you have and whats your goal but those brands make quality products that i have experience myself. If you only want your bike to get louder, you can choose anything that pleases your eyes. If you want power and good bottom end. Go with a bit longer 2 to 1 exhaust system.

Two brothers racing comp s 2 - 1 got a dip in the power curve at 3k but pulls hard in higher rpm (short 2 to 1 pipe)

I used bassani road rage gretz lutzka edition(double stepped version for bigger motors) for my 124 s&s twin cam and it did great along the whole range of rpms.

Supertrapp made the best hp and best torque of any of the pipes mentioned above. Quality was great. Bracket and fit was good too. Power curve was smooth as hell. In the other hand supertrapp was the quietest one with very low rumble and got louder after 3.5k with full throttle.