I've had this theory about my Civic... I think its rather loud for what it is...
I've had diesels that are quieter - this seems like there's either no sound insulation (or very little) or the exhaust is losing pressure somewhere.
It's not a "farty" noise, its quite pleasant when I'm in the mood, but it does get tiring on the motorway - was wondering if its one of the following:
1) Me not being used to it (tho I had a 2.4 accord which was quieter)
2) Being a new car, there hasn't been a great deal of carbon build up on the exhaust, so the baffles are resonating more
3) Something, somewhere is BROKED...! [smilie=cheeky-grin:
Of course, the sound doesn't bother me when and if I give it some, I know what to expect there!!![smilie=tongue.gif]