I don't like to use the phrase "above code". Something either meets code, or it doesn't. The code more often specifies the design and manner of installation, rather than some "quality" issue. For example, sanitary tees are wonderful fittings....but must be installed only where and how allowed. The UPC allows just about anything you can think of for water pipe. Not all cities, states, accept all types. You can get a bottle trap with an IAPMO rating, and within limits, the UPC accepts that.
One section of most codes will require (1) that material and fixtures be installed in accordance with the instructions of the manufacturer, and (2) that they be installed in a workmanlike manner.
SO there is a lot of wiggle room out there. This debate and discussion could go on forever.
I will mention a few things that are not universally "favored" by plumbers, for many reasons....some logical and some stubborn!
One piece combo angle stop and corrugated supply.
All of the above have IAPMO rating, and are accepted in some manner by one or more codes.
And just to put in a little dig here.....the three people I always shied away from working for: doctors, lawyers, and engineers. Too much trouble.