i dindt delete the egr( no real need in my own opinion), my light will come on after about ten minutes if i dont clear it first. I bought a code scanner from O'riely's for $60.00. if drive for less than 5-10 minutes i dont though a code. There are 2 moduels from bay area diesel, 1 is code free for $575 and the other throughs a code for $300, i bought this one because im gonna get the edge juice with attitude, and it will automatically clear my codes. So again i saved a little more money. At my mileage the exhaust will pay for itself in less than a year