stock turbos can make more than 16 psi on 2.5" exhaust. What do you mean "there's no need for more", more what, HP? I've personally tuned my previous and current Z on stock turbos with pump gas and race gas. I can tell you that the race gas allowed me to run a more aggressive timing map without detonation thus allowing me to make more hp.
Who has made more than 400whp on pump gas on stockers? I've seen a few with race gas but I can't remember anyone whose done it on pump gas without water injection or nitrous.
