I know I know, I ama noob, this is my first post hereas a matter of fact.

There is oneseemingly obviousthing thateveryonewho says "a smaller section in the exhaust system won't affect sound"is overlooking is the fact thatthis smaller section is forming aconvergent-divergent nozzle, which willINcrease flow velocity.(soft oflike aLaval nozzle, thoughobviously in thecase of an automobileexhaust systemthe gasses aren't going toreach supersonic speeds) This slight increase in flow velocitycould account for a change in exhaustsound.

Check http://en.wikipedia.org/wiki/De_Laval_nozzle for a little more info about how this couldaffect the gasflow.