carbonlaced

I have a 98 Civic Coupe with B18C1 Edelbrock B18C5 (Type R) Headers and custom 2 1/4" Header Back Exhaust with an RSR Style Baffled Muffler. As of now I get the standard Honda metal type buzzing noise from 3-4k RPM with a raspy noise in the piping as well as minor rumbling and back firing when I release the throttle. I dont have a resenator or cat is this the only reason im having this problem? , Also I plan on changing the entire system but dont know if the 99-00 SI Exhaust will line up correctly because of the length of the headers and could someone suggest one that would also be good for the supercharger going on in a couple of months?