The LeoVince system for the Gen3 is designed to work on a stock bike with no tune, according to their literature. If you change the air filter thats no longer true.
However you will need an O2 sensor adapter for the LeoVince, for some reason, the pipe thats made specifically for this bike has a larger O2 fitting than the sensor the bike comes with. No big deal $8 on Amazon so its clearly a fairly common need, but vital to this install! LINK
I would recommend applying some aluminum or lithium anti-seize to all the threads of the O2 sensor and adapter when installing, but carefully if any gets in the sensor its toast.
I have had the system on mine for 1000 miles and really like it. I have only run it with the quiet insert in so far and the throttle is responsive, fueling is slightly better 3500-4000 compared to before, and I really have not seen any significant change in MPGs. The sound of the motor is also greatly improved imo
If you pull the trigger make sure and get on an OEM parts site at the time and get a pair of copper exhaust crush gaskets. They are cheap and important to have a new one on with the new pipes so there is no leaking at the exhaust port.
I have not done the AIS block off (which injects air into the exhaust for CA emissions crap) and have noticed some popping from the exhaust on decel, but its been infrequent and minor it doesnt bother be like it has on some other bikes.
$500 is a great price I got mine for that price from a member here with no regrets