I also went the Akrapovic (cat-back) (I left the cats and down-pipes) so I second the recommendation of Mr. M6. So sweet... not crazy and no drone - doesn't wake the neighbors on early morning starts
As for cost, I was lucky enough to find a used system a couple years ago (somebody had it on a lease and took it off before they returned it), so cost was very reasonable. Maybe you could get lucky and find a used one.