GT2871R, GT3071R and GT3076R are all great turbos.
You choose your poison.
If 400WHP is your ultimate goal, go with GT2871R it will give you the widest power band with the most torque at 400 WHP.
I do not think you should try and make 400 WHP on pump gas. My rule of thumb is anything over 15 PSI you should step up in octane. You should make 360-370 on a VE with the GT2871R turbo at 15 PSI.
You choose your poison.
If 400WHP is your ultimate goal, go with GT2871R it will give you the widest power band with the most torque at 400 WHP.
I do not think you should try and make 400 WHP on pump gas. My rule of thumb is anything over 15 PSI you should step up in octane. You should make 360-370 on a VE with the GT2871R turbo at 15 PSI.