After searching & reading & discussing for a few months, I went with the Corsa track with stock cats.
Reasons in a nutshell: according to Corsa, who has no motivation to inflate or deflate the numbers, hiflo cats are worth about 4rwhp - for $600 & a potential pain to install - it didn't seem worth it, and I read some posts where hiflo's with a corsa or mopar, etc., were too loud or described as very agressive sounding. Having the exhaust tip 3 feet from my ear, I was afraid of being too loud, either for or my wife/son.
Install was pretty easy I thought. I did mine in the garage on jack stands, toughest part was doing it completely alone when aligning the tips and the sills, having a person help with that part would've been nice but all in all it's pretty easy to do.
Depending where you are, someone might be close that you could hear some exhausts, there are also posts with sound clips. IMHO the Corsa with stock cats is definitely not too loud, nor too quiet, and I wouldn't want it a decibel louder as I konw it'd be too much for wife to enjoy riding in etc.
Dave
03 SRT