I had a Stage 1 kit for 25 miles.
you can add larger injectors, a 5th injector or change the plenum out to get more fuel for a stage one kit(allot more cash here).
I would love to see someone get an actual 360(15+psi) hp out of a stage one kit. Not saying its impossible but it would be hard.
I would say lowered compression, 5th injector, straight race gas and a dump pipe with a shimmed wastegate you might see 350hp out of a stage 1.