Hey guys, I have access to a complete 6" exhaust kit that came off a 3rd gen Cummins that I am pretty sure I can fabricate to fit my truck. It is a straight shot from the end of the downpipe to the rear axle. The six inch is already bent to go over the axle so that will not be a problem. I know that is really big but do you guys think it would be OK to put it on? I intend to fab up a 4" downpipe because there is an adapter that will be right after the downpipe that goes from four to six inch. I have seen alot of talk on this forum about 4" exhaust systems. Is six even better? Or, is four inch sort of a happy medium for our old 1st gens? Thanks!

 

In my opinion Six inch would not be much benefit. The biggest restriction in these trucks seems to be the head and valves. Second: I won't say it can't be done but to get a six inch line past the tranny and transfer case is going to be a feat. The 4" pipe fills the space between the cross member and the frame just outboard the tranny and t case. About the only option is to drop down below the cross member at the down pipe.
I'm not sure if you have the tranny cooler under the turbo on the '89 but if you do the bracket that holds the cooler needs to be notched to fit the 4" down pipe. Also you will need to trash the heat shield that is on the 3". There isn't room. You can use the original bracket on the bell housing with a four inch downpipe but you may need to use a heavyduty hose clamp instead of the "u"bolt. On mine it hit the frame. The 3" to 4" bell reducer just off the turbo flange wound up being 1.75 inches long in my case. I even had to trim back the first elbow to get enough clearance for the fire wall.
I think that running a 4 to 6 inch line would be creative, but very noisey. It would work like a trumpet and amplify the sound. Straight 4" is pretty noisey on it's own.
Good Luck!

 

The real benefit in going bigger is in the downpipe. 6" inch is kind of, just for giggles. No real added benefit of a 6" over 5". just a different tone. From what I have seen/heard the other feet is clearing the shock on the rear axle. 4 is ok, 5 is a little tight. There r some funky bends to clear the t-case and cross member.

 

Before I do anything, I am gonna lay a real good eyeball to the situation. Anyone on the forum tried six inch exhaust?

 

Not me, I had enough of a challenge going to 4 inch

 

i say do the 6 inch it will be sick i would put it up as a stack
ya lots of noise make old ladys **** there pants lmao

 

It's a proven fact that the performance gain is very minimal after 4". The increase in flow from 4" to 5" is only something like 5%. Don't quote me. You have to remember the really big exhaust on diesels originated with rigs which have way more displacement and thus need to move much larger quantities of air than a 5.9 liter. There's no doubt that it would sound wickedly mean though!

 

I have a 5" exhaust. I used a Bully Dog 6.0L powerjoke kit. I have a 4" down pipe into a 5" at firewall straight to the axle. My 5" wouldn't fit at the rear shock so I made a bracket to move the shock further in at the axle. A little tight for axle travel even with five so 6" would be tough if you tow heavy or carry a load. But hey it would be cool to say you got 6" I guess, if you think it might fit make it happen.

 

I can get the six inch exhaust kit for under $200. Some kid bought it for a 3rd Gen Cummins and sold the truck. He took the six inch off and now he just says it's taking up space. I am gonna take a good look at it this weekend and see what if I can make it happen.

Fergavs, you say you bought a five inch system for a Powerstroke. What year, or are all the 6.0's the same? Thanks!

 

what does the system go for new? i say worst case pick it up (if it's complete) you can always throw it on the 3rd gen forum if you decide againse it.... like people said, gains are not huge stepping from 5 to 6 but for $200 that wouldn't buy you a whole lot of 5 inch pipe!

 

I'm gonna make a homebrew for mine. It will be 4" down and back to a 5" Donaldson that I got for free. Then its 5" out just for visual impact. and noise. I've managed to scrounge all kinds of pipe and bends and stuff and should be able to put it all together for peanuts.

 

On turbo charged engines, bigger is better. 6" wont hurt. remember 94 and newer truck have the drivers side transfer case. 93 and older has the passenger transfercase. Getting the exhaust past the Tcase will be a chore.
For the money its worth $200. If you want that 6" bad enough you can do it. If it works than let us know. Fair warning, it will be a big job.

 

Well shoot, for 200 bucks, if it just dont fit, throw it in the classifieds for 300 bucks n it'll sell pretty quick immagine, its pretty well a win win situation.

 

Yes all 6.0L are the same. I think Bully Dog only sells one part number for those trucks in a 5".

 

I have a 5" from the turbo back DP and all. Take out the upper suport bracket on the trans crossmember and there is all kinds of room. You don't really need that part. Hey cowboy are you OK? I heard about your wreck and just saw the pics. How did you get out of the truck? It looks like the steering wheel is pretty close to the seat. Hate it when those trees jump out in front of you like that.