Nismo 370z vs. Standard 370z - Same aftermarket parts, any performance difference?

scruffydog

I've always wondered if 2 people purchased the follow cars:

A) Nismo 370z - 350 hp
B) Sports 370z - 332 hp

and each of them starts modifying their cars with the following upgrades...

A) Nismo 370z
-Stillen G3 Intake
-FI Exhaust (Replace the OEM Nismo Exhaust)
-HFC (Replace the OEM H style downpipe)

B) Sports 370z
Stillen G3 Intake
-FI Exhaust
-HFC

Aren't these 2 cars essentially the same car in regards to performance since Nismo 370z harvest the extra 18 HP is from it's Exhaust system and a minor tuning?

Or will the Nismo still better performance because it was factory tuned differently?

Correct me if I'm wrong but is this case like a STi vs a regular Subaru WRX and a Subaru STi, or a regular Civic vs a Civic Si it is not the same car in performance unless you either buy a different engine block or a different turbo, etc.

Keep in mind, I'm not talking about Suspensions or the Aero kit as there are a few things that don't neccessary focus on the Engine performance which the Nismo has over the Sports 370z that I'm aware of.