Honestly, if you maintain it properly, check fluids etc, you're going to be fine. Subaru would also deny a claim on a completely tock car if the engine goes and they see you were hooning around in it prior to the event.
I believe the Subaru dealer in Milford, CT is pretty chill when it comes to mods. I swear I've seen some Perrin gear in their parts store.
I was working at Toyota just up the road from this dealer, hearing a story about one of the service advisors friends....bought a 2012 (only a year or to old at this point in time) bone stock, and denied his warranty claim after grinding his engine. Why? Because looking through his ECU they could see multiple redline hits, and some WOT all prior to blowing it
Lets be honest. No one really buys these cars without wanting to have some fun with them. Whether it's some track days, mods, or no mods plans but just a fun little weekend car, the warranty will only be honored if the failed part failed in the way it's designed to work....so any signs of abuse, stock or not by itself is grounds to deny your claim.
Now, that also isn't black and white either. It will always depend on the dealer because some are more willing than others.
Thanks for the responses. 
