I had a power flow stainless custom made system, really good quality etc and would have outlasted the car easily. Trouble was, boomy wasn't the word and it didn't suit the character of the car at all. The stock rear silencers do all the sound deadening which explains the size of them, so if the replacement has smaller round cherry bombs, be suspicious!
I also remember the car sounded good and not too loud outside, but got much louder and boomy when you got in.
Note that the stock Center silencer does very little for noise reduction as it's a small straight through box.