I'll agree with all above. When I bought my MV6 it had a new exhaust recently fitted, so I thought "great means I probably won't have to replace it during my ownership". Wrong -- it was noisy whenever I put my foot down, and not a pleasant noise at that, more a drone. It was worst at between 1500-2500 RPM, which is an almost unavoidable rev range to use when driving in town and slow traffic. I often found myself revving it up in first then shifting to third to keep it out of that rev range trying to avoid the dreaded drone.
In the end I removed a perfectly "good" exhaust system that would probably have lasted at least a few more years, binned it and had a GM system fitted. The car is much quieter now and as a result my sanity is intact.
It's a perfect example of the truth in the old saying "do the job once -- do it right". Find someone local to you who has a Trade Club card and the bits aren't that expensive.