I would like to replace the stock mufflers on my 2008 Subaru Impreza WRX STi. Is Flowmaster a good choice?
if you roll around in a 78 Z28, Series 40's are the way to go. For what you would spend for a quality install, I'm certain you could find a bolt-on set for cheap.
I'm not sure what your budget is, but I would advocate purchasing a used, model specific exhaust from a name brand such as Cobb, Greddy, Nameless, Invidia or even Subaru SPT.