I've got a Q300, I tried a Test-Pipe, and it lasted a week, OEM cat back on now.

The Q300 with an OEM cat has a nice characterful noise; you loose that with the test-pipe and it just becomes obnoxious and loud with very little tune.

You've made the correct choice to stay as is

 

I have the q300 with TP and have only minor rasp at about 3k rpm. Otherwise it sounds good - heard it myself when I had Jordan take it for a test drive to make sure she was in tip top condition and liked the sound. Each S is going to be unique in regards to mods and sounds. It might still be worth the purchase (fairly cheap) especially if you plan on more mods later on.

 

I'm probably the only one on this forum that likes the sound and smell a TP creates. I am getting it tuned shortly though.

 

TPs are not worth the hassle imo, especially on an S.