My cummins on the dyno, 546hp 1188 ft-lbs..

[Redneck]

I hate auto tranny's, but I hear the 6 speed is doing better than the old 4 speed. Even then, you will want to put $5k or so in the tranny if you are going to add power. The Allison auto in the Chevy's is supposed to be the best factory auto tranny avalible, and I have seen some adapted to fit a Cummins. They are still breaking if you add 100hp or so to the truck. If you do anything to make more power, you need to get a torque converter and a upgraded valve body. Even the Allison was breaking imput shafts with about 200hp over stock. I broke 2 imput shafts on my 6 speed standard before I bought some titanium and borrowed a shop. Then I had it cryo treated. No problems with it yet, but Im having clutch slip issues. Waiting for my tripple disk before I add any more power. I have dual CP3's, twin turbo's and some more go fast goodies waiting though. 1000+hp to the wheels without N02 is my goal. With go-go juice I am looking for over 1500. I bought another trans for this truck that Im going to tear down, and remake everything in it out of titanium. Hopefully that will take the power I am planning on. I almost have the back-half done too. Going with a 4 link with coil over shocks, but it will have airbags for towing. Right now the truck will break traction bars and leaf springs if I launch too hard. Just like fast boats, having a big slow work truck that will beat dedicated race cars is an obsession. I will see if one of my friends can email me some pics he got of me launching. Getting one front tire in the air off the line. Problem is the leaf springs are breaking when I do that. It never ends, but I WILL have the fastest diesel in the country sooner or later.

[Redneck]

Oh, the 6.7 has an exhaust "filter" that you are supposed to have "serviced" every so many miles. Supposed to keep the truck from smoking too bad. I would see what it would take to gut it. Remember, with a diesel, back pressure in the exhaust will make the EGT's higher and will take several hundred throusand miles of life from the engine. Taking the muffler off the old truck will add 200,000 miles to the life of the truck easy.

[Casey]

I've got a 04 (305/555) 2WD, DRW, QC, 6spd that's stock expect for a 4" Magnaflow muffler, Power Pup and a gutted intake silencer. do ya'll think it's worth swapping to a true 4" turbo back or is the 3.5" down pipe plenty for what mods I've got.

[Redneck]

It should drop your EGT's a little and maybe give you a small fuel milage increase. Up to 1mpg or so. Depends on what you expect for your money. If that is worth the price of the exhaust, then do it. Kind of comes down to what you want. Might pick up a little power and I believe it will get your turbo to spool up just a little faster. Probably not that noticeable to the driver, but if you ever take it a little further, you will already have what you need.

Did you gut the plastic piece between the airbox and the turbo? Have you taken the silencer ring out of the turbo? A big circlip holds the little stamped piece of sheetmetal in the intake of the turbo. Gives you a little smoother intake flow, and more turbo whine. Supposed to give another little bit of power (not really noticeable) and its free.

[Casey]

yes, I took it apart and removed the cross piece and then put it back together. I wanted it to look stock for warranty purposes. since it's now out of warranty I may pick me up a piece of 6" tubing to replace it with. and I've thought about removing the ring but decided to leave it in to keep it quite

one of these days I may do more but only after I replace the clutch. it can't even handle what I got now. I have to leave it on the 90hp setting to keep it from slipping

[Liquid Force]

Im not a fan of auto trannies, but alot of people drive my truck, and driving a LHD vehicle in a RHD country it's easier to just deal with an auto, changing gears with your right hand feels a little strange.

[Redneck]

Casey, yea, the older 6 speed (NV5600) doesnt like power without a clutch upgrade. Get that done, blow some 'Stangs and Camaros away and you will want more. LOL. I have the G56 (05.5 and later) and it takes power better, but still doesnt handle what Im throwing at it. Waiting for my tripple disk. Price for me, as a beta tester, is $3200, so not the cheapest thing around.

Liquid Force, that my no one drives my truck. Big turbo likes to bark bad if you dont know how to drive it, so no one else touches it. I like rh drive cars. But Im left handed and got used to the shifter on the left pretty easy. Im better with LH drive though.