To actually answer your post...
The STS kit in itself really isn't too bad. Like bradley said, some of it is poorly engineered. If you can pick a used kit up, that would be your best bet. For the "retail price" you could build your own custom system with better quality parts.
Pros:
--Sounds firetrucking INSANE (INSANE!!!!!!)
--Makes good power
--Cool to show people a turbo under your fender
--Clean engine compartment
Cons:
--Some pieces poorly engineered
--When something does go wrong, you have to work on your back
--Slight boost lag (very slight.. not really such a bad thing)
--Definitely not worth retail
--Customer service can be shoddy (spent weeks waiting on a part to find out it hadn't even been ordered, although their technical guys are always around and very willing to talk)
--Low clearance in the back (can be a pain sometimes, can't back up onto a ramp, etc)
Pro/con:
--While it sounds insane, it's a little loud for me sometimes.
So, if you want something unique that will turn heads, sound like a goddamn spaceship, make decent power, have 100% stock driving characteristics, and sweet blow off valve, but have to deal with fixing shit from time to time, it's a great kit.
I'm currently making 471/491 @ 7.5 through an A4 without meth with a very conservative tune. So they "work".
P.S. I might be selling mine :angel: