Just got a new 2006 Chevy CCLB with the Allison 6 speed. Just trying to sort through all the aftermarket stuff, to see what would give me the best increase in MPG without too much of an increase in exhaust sound. Would removing the cat and installing a more free flowing exhaust do the trick, or will I want to get into electronics as well? I mainly tow my horses around the northeast and bought the diesel for the power and better fuel economy than a gas. So far I love the Dmax. Have pulled a Kingston trailer with 2 horses and tack for around 700 miles total and am averaging about 13.2 MPG. Any info would be appreciated. Thanks

Steven

The 06 is so new that you are going to have to be you own testbed. Most of the basics should apply, but GM and the goverment are going to make it harder to play with every year. The 13.2 does not sound that bad pulling. My last tank pulling with my modified 05 was 12.1 and it was one of my best. There are a lot of variables.

Thanks Rick. The basics being, the easier it breathes the better it runs? I figured I wouyld start with a down pipe and exhaust and see how it goes. If then I need more power, move into electronics.

Definetly losing the cat will help the engine breathe better. You will probably drop about 50-75 degrees EGT too, which is always nice when towing. However, if you lose the cat, the EGR system will throw a code and the check engine light may come on. To prevent the engine from throwing the code, you can buy a "Finger Stick". It basically kinda fools the EGR system into thinking there is more back pressure present than there actually is (becuase there will be a LOT less when you lose the cat). I think the exhaust MIGHT have changed slightly for 2006 but I think one fellow figured out how to make it work. Losing the cat and upgrading to a 4" exhaust will definetly gain some HP, but most of all, drop those EGT's, which is better on the turbo and engine life. The air filter on the 2006 LLY's is completely new and MUCH improved over the older airbox's. I personally would leave it alone, its a nice setup. As far as electronics and chips, the 2006 LLY's are kinda out of luck unfortunatly... For 2006 they switched over from the old pea-brain 16 bit Delphi/Delco PCM's to brand new 32-bit Bosch PCM's. This upgrade in PCM/ECM helps the engine run better and also simplifies things in the engine because the PCM and FICM/EDU (fuel injection control module/engine drive unit) are integrated into one unit, whereas on the 2005 and older engines, there were two separate units. This upgrade in PCM's means that tuners and chips for 2005 and older LLY's will NOT work with the 2006 LLY's. In late September, the engine is being completely overhauled and redesignated the [RPO code] LBZ Duramax. It is unknown whether aftermarket tuners will make any chips for this "interim" engine. The PCM used on the "temporary" 2006 engine is supposed to be similar to the new LBZ computer, so it MIGHT be possible that chips designed for the new LBZ will work for the 2006 LLY engine... But as of right now, the only performance mods avalible for the 2006 LLY are exhaust, and removing the catalytic converter. Hope that helps!

----Ben

Thanks BEn.
It is me here with the Westbrook Hunt Club girls. How do you like the MBRP? I was thinking that or the BAnks. Don't want it too loud b/c of the wife and kids. Hope school is well. Also sent your dad my emial to sent up to you. Thanks
Steven

Ohhhhh!!! Hey Steven! I thought that might be you...my mom told me that you just got a Dmax. Thats awesome! How do you like it so far? I definetly want to check out that 6-speed Allison when I come home! I love the MBRP dual exhaust. It has enough "grunt" and noise to sound cool, but it does NOT drone at all inside the truck. I hardly notice it inside the truck unless I really step on it. I went with the 409 Stainless steel dual cat-back set. ~700 dollars from www.xtremediesel.com. It has a 5 year warentee, but for another ~400 dollars, you can get the dual 304 stainless kit...lifetime warentee. It was really easy to install, I didnt have to cut it or anything, and the truck is so high off the ground that I could just crawl right under it. The only pain was getting the stock exhaust out. I ended up just cutting it off because I couldnt maneuver it around the axle to slide it out. When I come home one of these weekends, ill let you know so you can take it for a drive and get a feel for the noise level. The cat-delete pipe is another 100 dollars or so if I remember correctly. I didnt bother with that yet because I knew I would have to install a Finger Stick to stop the EGR system from throwing a code and Check Engine light. School is going well, I hope all is well down there! Tell everyone that I say hi!

---Ben