Please dont' take my work for this, google "the myth of backpressure"
Exhaust pipes, crossover pipe, muffler and baffles, are tuned to a given engine like a church's pipe organ. At low to mid-low rpms each 'plug' of exhaust traveling down the pipes actually draws a partial vacuum in its wake efficiently scavenging the exhaust at the head. Altering this tuning spoils the exhaust scavenging leaving some excess exhaust behind in the cylinder to spoil the next stroke. The effect is losing some torque at low to mid-low rpm. It is mistakenly attributed to "not enough back pressure" on the theory that opened up pipes exhaust better, but that is actually the opposite. With the pipes de-tuned the scavenging is not as efficient and the backpressure goes up.
Now the bike will run fine enough, but if you want the best performance, do your research on aftermarket that has been specifically engineered for your model.
Last edited by Kryton; 06-18-2019 at 11:09 AM.