My custom 3" mandrel exhaust is getting a bit too loud for me. It has no cats, no resonators. Just a magnaflow 3" straight through muffler and a custom HUGE turbo elbow. What would have the largest impact on making the exhaust alot quieter? A cat? A resonator? I really don't wanna do both and I know a cat robs alot of power but if it makes the exhaust alot quieter than a resonator then I guess I'll do it. Suggestions?