I have a silly question. I have a 04 LLY crew shortbed. I run Geolander 285's, bullydog programmer set on "extreme", volant cold air intake & a turbo back MBPR exhaust. All mods were put on the truck "DAY ONE". Why after putting 20k miles on the truck does it run better than ever?!?!? My fuel mileage has gone up & I have changed nothing! I am religious on my oil changes & fuel filter changes.

Do these Duramax's brake in @ 60k miles or am I loosing my mind? I have a heavy right foot every now & again & do a ton of highway miles but still see nearly 20 mpg. When I first got the truck I got 17.5. What gives?????? IM NOT COMPLAINING, just curious!!

Hands down best truck I've ever owned.

Thats the beauty of a diesel. Unlike your toyota camry that breaks in at 1500 miles, it will take between 20-30K for your rings to seat and everything to break in. Usually about 30k it will start running at peak

I tell ya, I couldn't be any more impressed. My last truck was a 05 Cummins I blew the tranny, differential & 2 shafts & hubs @ 21k miles, truck before that was a 04 crew powerstroke I blew the head gaskets.

I've had this truck for 6 months & normally thats a long time for me - I couldn't be any happier with this duramax. Performance is awesome, tows my 28' trailer like a dream, fuel mileage is amazing and the ride is second to none. I've thought a few times of upgrading to a LBZ 06 or 07, but I can't justify spending 5-10k, then doing programmer, exhaust, tint, remote start, tires, service etc.... to have the same truck with more power. Sorry to ramble on, just finally satisfied with a truck!

I've usually traded trucks every 2 or 3 years. The current one has performed far and above any others I've had. Think I'll hang on to it for a few more years. 52K and runs better every day.

I have a silly question. I have a 04 LLY crew shortbed. I run Geolander 285's, bullydog programmer set on "extreme", volant cold air intake & a turbo back MBPR exhaust. All mods were put on the truck "DAY ONE". Why after putting 20k miles on the truck does it run better than ever?!?!? My fuel mileage has gone up & I have changed nothing! I am religious on my oil changes & fuel filter changes.

Do these Duramax's brake in @ 60k miles or am I loosing my mind? I have a heavy right foot every now & again & do a ton of highway miles but still see nearly 20 mpg. When I first got the truck I got 17.5. What gives?????? IM NOT COMPLAINING, just curious!!

Hands down best truck I've ever owned.

Running any diesel on an "extreme" setting SERIOUSLY affects the longevity of your engine. It may run great now, but if longevity is what you want, it won't happen. Read about other guys who ran their programmers on the highest setting day in and day out. It's one thing to drag or pull with it, but doing what you are doing is different altogether. Good luck. Besides, GM doesn't exactly step up with warranty issues.