Please help with exhaust

[DiCaprio]

Bare in mind that without a resonator (Part B) you might get some nasty frequencies that lead to loud buzzing and droning which can get really annoying over time.

I found a good explaination between the difference between a muffler and a resonator on the internet:

Mufflers:
Lowers sound level
Usually packed with fiberglass
Does not eliminate certain frequencies of sound (droning)
Increases engine back pressure, hampering performance

Resonators:
Almost straight pipe sound level
Cancels certain frequencies to stop droning and obnoxious noise
Not adjustable at all, you either like it or you dont
Decreases engine back pressure, increasing performance