I went to an exhaust shop a few days ago and had some work done. The welder removed my catalytic converter system and welded up a new catless Y-pipe assembly with bungs for my four O2 sensors. I made MIL eliminators for the downstream O2s (working great!) and it got rid of my PO420/PO430 codes that have been plaguing me for some time now. Needless to say, the exhaust is much louder now. It does has a nice Roush GT Mustang rumble at idle, but when the engine hits a certain RPM I get a resonating buzz (for a lack of better description) coming out of the tips. I was more than happy with the exhaust dB and pitch before this mod. I run a Delta 40 series catback by Flowmaster, which I do not plan on changing. I spoke to the exhaust shop and they recommended a long glasspack after the Y-pipe to cure the problem. My only experience with glasspacks are with my friends' old pickups. Do you guys think it will quiet it down and remove the raspy buzzing?