and...
those hoses connect the exhaust to the egr tubes which feed the exhaust gas through the egr valve. the exhaust gas recirculation valve puts that gas in the intake manifold and the engine reburns it which lowers cylinder head temp thus lowering nox. it's a different world from emissions to performance with a pretty thin barrier. performance car you would want cold/denser air ingested into the engine giving more power and engine running leaner, but with that comes higher nox. by recirculating the hot exhaust gas the air in the plenum is not as dense therefore the car's not going to run as lean thus lowering cylinder head temp and nox. also another reason you'll notice on nissan motors how it has coolant running through the throttle body. just wanted to help you understand the WHY in how does shooting hot gas into my engine cool it down. personally though i still think your nox is too high to be just egr related, i'd still recommend sourcing some cats.
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