Exhaust note change??

Question... I noticed tonight that my exhaust note seemed to change when accellerating hard and in 3rd gear. It went from super loud and raspy at WOT to more tight and not so raspy. I also felt a little resonnance in the gas peddle? Is it possible that the headers and the higher tempertures are changing something in the Dinan cans? The cars still seems to run just as strong but sounds a little diffrent in 3rd gear at WOT.

Maybe I am losing my mind. My fiance` thinks everything seems the same (as she was receiving a case of whiplash). I think she just wanted out of the car though, so much for a second opinion.

Anyone else expereinced a exhaust note change with headers or some other issue? Also some sort of ressonance in the gas peddle at WOT? I felt this right after the headers were installed but seemed like it went away. It is only at WOT with the peddle pinned aginst the floor. I have no idea. Probably will be back to normal tommorow but thought I would ask.