headers made quite a huge difference to the sound in my crossover, which wasn't that noticeable to begin with either being a jdm b18c
the crossover was there, but the headers just made it sound a whole lot better.

cai allowed me to hear both vtec and the dual stage
2.5" spec2 with muffler; could only hear vtec but rather lazy kinda sound.
with headers now it's very distinct.

i suppose with honda's when you're talking about i/h/e, it's not gonna give massive gains, but rather shift the powerband to where the engine produces its power best.
thus, upon installing such mods, there is more gains to be felt in vtec or maybe even a little loss down low.