Resonators are made to be used with mufflers. I see them a lot on newer vehicles. My 90 model VW (RIP) had one before the muffler and was relatively quiet. I had it removed and it was just a tad louder. My 99 Montana has one right after the muffler and it is dead silent.
I believe they are used to help tone down the sound. If they are before or after the muffler I don't think matters. A resonator by itself does sound awful. Our 87GN has straight through design mufflers, almost identical to a resonator. A pair of 3" pit bulls from ATR in SS. To me it sounds great, but I like a some sound.
If you use the resonators with a pair of mufflers, it should be right quiet. Yes, the flowmasters are restrictive with the turbo. They are made for a different purpose. There are may choices for mufflers. Many here have opinions of different brands, models, etc. I would think a straight through desing or a pair of turbo mufflers in the typical location crossed to a pair of resonators in the stock muffler location would be interesting. I haven't ever seen or heard of anybody doing this.
Hope this helps.
