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Staying NA will take a lot more than that to hit 400. There is a shop on here running around 372whp na, but thats a crap tone of money. They have every part that you could imagine on theres plus a bunch of custom parts. Best bet it to go fi ams call it a day. Get a nice supercharger with supporting mods and be happy.
Hey man sorry to break it to you but the mods you have listed wont bring you even close to 400. Throw some internals on there and then come back
Cold air intake - Dont bother, if your going to do an intake do a pop charger. 10hp
Headers - depending on the brand roughly another 10hp
Exhaust - Borla claims "independent studies" show 20hp gains, 10-15hp is more realistic. We'll be generous and say 15hp
ECU chip - Didnt know Nismo made one of these? anyways prob around 10hp
So with all your mods your looking at a grand total of a 45whp gain (being generous) and still under the 300whp mark. NA builds are expensive, hope your prepared for that.