Welcome mate
PPP, well it all depends if you are worried about your warranty, there are cheaper and better ways to get that power (and more) but if you want a warranty then it has to be PPP
I've been running over 300bhp on my 2004 WRX and have no problems at all, remember Subaru's are reliable if looked after and serviced properly but there is always a chance something could go wrong (didn't bother me though [])