Safest way to go stage 2 is to get a catted 3 inch bellmouth or divorced wastegate downpipe and catback exhaust of your choice (whichever you like the sound of). Install, reflash, and enjoy. if you want even more piece of mind for safety you should get a pro tuned map. A tuner can load a custom map onto your ap. I'm not sure about tuners in your area but you can either get a street tune, dyno tune, or e-tune. Are you wanting 300 hp to the wheels or at the crank? There is a substantial difference between the two. Im not sure 300 hp to the wheels is possible on the stock wrx turbo with only a stage 2 tune. I could be wrong though. Someone els can probably chime in on that. Happy modding!!
06' wrx tr