I had one on my WRX when I bought it. It sounded really nice. I don't know how much louder or "flowy-er" it is compared to the stock exhaust tip since (as I said) it was already on my exhaust when I got my bike.
That said, I now have a Q4 and it is louder. I'm not sure how much better the Q4 is over the Graves Hi-Flo insert since I did "all the mods" at the same time, so while I saw a difference, it was not only due to the exhaust change.
It is expensive for "just the tip", but does give the stock can a nice bark.
That said, I'd save up your pennies and go with the Q4.