RHC

What year trucks can I use the cast Iron turn down to install it on my 2003 to have a 4" exhaust system all the way back?
Will the cast iron turn down off of a later model fit on my 2003 with no modifing?

tn hillbilly

04.5 and newer.

Marshall

lniemeyer2

Yes the cast iron turndown for a newer truck will work. I recently upgraded the exhaust elbow on mine and the best place I found for parts was the dealer believe it or not. The elbow was $62 and the clamp was $19, shipping was free and I got a down pipe from the classifieds on here. Here are the part numbers for the dealership.

elbow for the 4.5-05 years 5161570AA
4" downpipe for the 04.5-05 52121600AA
Clamp for the above 52121285AA

The you can have a straight 4" pipe welded up to a muffler with a 4"inlet outlet.

SOhappy

Did you notice a big difference in mpg/power after the 4" mod?

Hounddog

Back when I did mine I noticed a instant mpg gain.Mines been since late 03.My elbow is a Banks since that was it ack then.

HotRodK

Im impatiently waiting to get the cash to do this. Sounds like a great mod for the '04s.

RHC

Let's say i get a 4" cast iron elbow for my 2003. Now when i go to order an exhaust system form MBRP, do i order the exhaust system for the model year that the cast iron elbow was for, say 2004.5 or do i just order it for the model truck i have?

HotRodK

I think you get the one for the '04.5 since its 4" all the way.

alluebbe03

I recently received my 4" all the way back kit for my 03, but don't have it on yet. I got it from farmboysdiesel.com. It bolts right up to the original elbow and I don't think just the elbow will make that much difference; the exhaust is coming through several smaller points coming through the turbo. I really like the looks of the system and free flow muffler and think it was a very good value. I am hoping that this will fix the weakest link in getting a bit better breathing and mileage from my truck. I will try to post again when I get it installed...

C Schomer

First, I went to 4" from the DP back and later on I pitched the 3.5" elbow and built a 4" DP right from the turbo flange. IMO, I don't think it's worth the $$$ for the 4" elbow unless you have a lot more hp than mine. Craig

lniemeyer2

I already had my donaldson exhaust on and didn't really notice any power or MPG increases. I did notice a little cooler EGT and quicker EGT cool downs when shutting down.

C Schomer

The 03 muffler is very restrictive - mine was choked down to 3" inside where i couldn't see it til I cut it out and looked inside. Once I put on the 4" muffler and ran 4" from the DP back, the egt dropped and the hissing went away. The 4" elbow and DP change was hardly noticeable. I already had enough pipe to build it otherwise I wouldn't have done it. Even when I had my 97 which only had a 3" DP, the 4" DP change made very little difference for my medium hp range. Craig