Another vote for Cobra here. I have a resonated system on stock Y-pipe at the moment and it sounds lovely. There is a noticeable cabin drone at 2-2.5k RPM but you can easily change gear to avoid that, it doesn't really bother me. I absolutely love the little pop it makes when you let of the accelerator in 1st and 2nd. I do feel sorry for the neighbours when I start it at 6am, it's bloody loud on a cold start up!!