On a stock or mostly stock motor, the smaller the baffle the more low rpm torque and the quite the exhaust. As the size goes up the sound goes up, but due to less back pressure the low end torque is a little less. This is especially true on M8 motors.
I have considered trying the 2.5 on my bike as it wasn't available when I built my motor. But I love how hard my torque comes on early with the 2.25. Understand my motor is very built, 163 HP and 167 torque.
We tried the larger cores on my 2019, and ended up with 1.75 cores after some dyno testing.
Very little change in HP readings but I liked the TQ curve with the smaller baffles, plus a quieter sound.
This bike is my long range touring rig.
I have the 2.25 cores on my other bike.
True dual setup, yes, louder.
It “sounds” faster! and pulls harder as the revs climb.
Both bikes are total Fullsac exhaust systems.
Totally different builds on different bikes. Best to go with what your engine builder suggests, if not a stock motor.
JMHO of course.
