Hello all: I have already sent 06monteSS a PM with this issue and a few other minor questions and I'm awaiting his response. However, I just wanted to throw this out there and see if anyone else had this issue and knew a remedy... I just installed the 87 Octane Tune into my 03 5.3 Silverado and noticed a great result in performance...after about 20 miles the engine light has popped on but without any decrease in performance...anyone else experience this? Some of you may remember this happened to me after the 57 Series intake installation but it went out on its own and has not returned until now. I am going to swing by my buddies garage and put it on the code reader if no other remedy is known....thanks for the help. :great: JAY ---------- Post added at 08:31 PM ---------- Previous post was at 08:00 PM ---------- OOOOKKKAAAAYYYY!! The D@*N thing went off again!! I just went down the street to grab a sandwich and when I got back in the truck it was gone! Oh well... the truck is F'ing with me...again! LOL! Hopefully it stays like this.