exhaust buzzing sound

[subru92svx]

Well I finally had my new Magnaflow exhaust put on today and it sounds good. The only thing I don't like is I'm getting a buzzing type noise toward the front half of the car right around 3000 rpm. It might help if I told everyone how I had the exhaust done. I had the precat pipes cut right after the O2 sensor hole eliminating the precats. New piping was then put on after the O2 sensor hole leading to a dual 2" in single 2.5" out catalytic converter. From the catalytic converter I had 2.5" piping running to a resonator/glasspack and then into a 2.5" single in, dual 2.25" out muffler. As far as tips go I had the exhaust shop widen the hole in the back of the stock exhaust tips to fit the 2.25" piping then welded on. Looks nice and stock, but doesn't sound like it. I was thinking noise might be from the heat sheild on the new catalytic converter because it is around the area where the noise seems to be comming from, but could eliminating the precats cause this? I was also wondering how I might be able to make it a little louder without making it sound bad. Maybe remove resonator and do different tips? Any help would be greatly appreciated. Thanks