[Def]

Your Mazworx manifold is just fine. IMO, twin scroll gives a slight boost in VE, but it's nothing that a little time on a dyno with cam gears couldn't find (or more gains) and no one even bothers with that in the Nissan world for some reason. Twin scroll is expensive given you already have a decent single scroll setup.

IMO, a regular GT3071R will do about 450 rwhp running it to death, but the GTX3071R will do it much more comfortably. The biggest difference on the billet wheels is the smaller hub boss, so they have a little more flow area, and you get roughly GT3076R flow for about the inertia of a GT3071R.

Your biggest issue is the 2.5" exhaust, definitely make that a 3" exhaust with good mufflers and you'll see huge gains.

The GTX3071R will definitely outspool your old T3/T04E, so I wouldn't worry about that. I might even think about using a 0.82 A/R hotside personally, since that is a better fit for a >400 rwhp KA IMO. But if you're mostly on the street I think you'd like the 0.63 more.