The R428 engine was designed before the high levels of egr required to meet 04 US emissions were implemented. This engine was designed to run with little or no egr originally, which means it ran at higher in cylinder temperatures and pressure. It's built to handle that operating condition. The SEGR simply restores that original, more efficient operating condition. With the idle air to fuel ratio running very lean on a diesel, it's a moot point.

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2005 LTD CRD RB1 NAV/Htd Leather seats/Amsoil EA filters
SunCoast Mega Trans & Billet TC/PML pan/Aux cooler
Fuel cooler/Lift Pump/10um Pri/Racor R490 2um Sec Fuel Filters
IronMan Lift/Shocks/Provent/Moog ball joints/ V6 Airbox/Fan/Hayden
Cobalt Boost/EGT/Oil/Trans/Volt gauges/Aeroturbine 2525
Yeti Hot Tune/Odessey 65/Samco's/Michelin Defenders