550 Tubi worth it horsepower mileage etc

I'd appreciate hearing from anyone who has installed Tubis on their 550. I'm not interested in impressing people at a stop light (the car does that already-- even to the point of inciting testosterone poisoned boys to show off in their what-cars).

I --am-- interested in better performance on the highway and better mileage. I guess I'm bothered by the idea of the exhaust being to loud on the highway to enjoy the ride and music and so forth.

Thanks, John