02-05 WRX's have a Catalytic convertors in the uppipe that have been known to break apart and damage the turbo fins. Aftermarket Uppipes mostly run around 140-200 for a well known brand.
If you pick up a new one make sure to buy new gaskets for uppipe and for the header if you go the route of removing the header to remove the uppipe then pick up new gaskets for that also.
Check on Youtube for install videos if your thinking of doing it yourself.
Ive been looking into removing my uppipe also,was thinking bout the Invidea UP.
Hope this helps ya out man.
Cobb Accessport Stage 2.
Never trouble trouble, till trouble trouble's you.