Hey guys,

I have a 2001 cummins with an edge ez chip and 60hp over injectors(was told it would boost my milage a bit), otherwise the truck is stock. Don't pull much at all just looking for decent milage and a good sound. Looking at an MBRP 4" or 5" exhaust system with their muffler. Any opinions or does anyone have experience running the 5" compared to the 4"? Pros and cons? Help me decide please!

 

I think 4" is good to 500hp. I bought the 5" to keep my egts as low as possible. My bro has 4" but 3rd gen. Hard to compare two diff CTDs.

 

5" is overkill unless you are running twins at 600+hp. But every truck I see around buys it. It was dyno proven years ago that 5" is actually less effective at reducing EGT's than a good 4" setup due to flow dynamics in the pipe.. But I Digress...

Fact is with your truck, if it has the HY turbo, the exhaust is the last of your worries. The biggest restriction is your turbo. Most exhaust system "upgrades" are only good for 75-100°F drops in EGT's at the best of conditions. My opinion, get a good 4" and worry about saving for a turbo.

 

Looks like i have a Holset turbo? Didnt know they put those on as stock turbos. Does the 5" exhaust really sound that much different than the 4"? I can get a 4" stainless system for the same price as a 5" aluminized. I am leaning toward the 4" now because of cost, just dont want to regret putting the wrong system on. Thanks for your knowledge fellas. Keep the opinions coming.

 

Ron Allen did over 1000 hp on a 4" exhaust. No spray, all fuel!

 

Over 200,000 miles on my 4 inch with no problems. Why does this sound wrong?

I tow heavy, work the old girl on a regular basis and heat is not an issue. Your going to drive it by the pyro anyways.

Like everyone says and I agree, go 4 inch and save the rest for a turbo down the road. Doesn't matter if you use sewer pipe for exhaust, the turbo is the biggest restriction.

With the 4 inch, you will gain flow....air in means air out. I wouldn't hold my breath for any huge mileage gains, but it will help when you factor everything else in....in all adds up.

The latest and greatest or the biggest isn't always the answer.


Jeff

 

I'm not saying it can't be done, it just seems to be the default answer. Everyone has their own theory, pick what works for your $ range. When I bought mine price/size wasn't an issue.

"Doesn't matter if you use sewer pipe for exhaust, the turbo is the biggest restriction."

 

There are two different models of the Holset turbo for the autos. For a brief couple of years, a smaller HY35 turbo was installed on the auto trucks for emission control. The standard turbo up to that time was the HX35.

The main difference is the HY35 is a single inlet turbine housing with a flow area of 9cm2 and was only capable of reliably putting out 35 psi of boost without coming apart. The HX35 was a 12cm2 flow area dual inlet turbine and was capable of over 35 psi, not much, but much more reliable. And like was stated the 12cm2 flow area is bigger than the 9cm2 flow area, thus, more flow and better EGT control for more HP.

Here is some info on the different turbo models of the Holset on the CTD.

http://www.dodgeram.org/tech/dsl/FAQ/turbo_faq.htm

 

Thanks guys and thanks Lil dog for the turbo info.

 

i got a 4" turbo back straight pipe on my 95 and luv the sound it gives....never too loud.....as long as i stay out of the ressonant rpms but honestly i don think i would change to something else if i could, unless it was free.

ps its a mbrp

 

I have an MBRP 4" on my 02 and I love it. EGT's are pretty low. My dad has an MBRP 5" on his 03 and his EGT's are lower obviously. They both have a great sound. I like the 5" better I just didn't need it for my truck

 

I personally like how big the 5" looks cause these trucks are so big and a really like the deep low end.

 

I have a 4" on my truck, and if I remember correctly, the stock turbo outlet becomes the restriction on anything bigger than 4."

 

I really like my 4" (err, exhaust, of course) from MBRP. When I first got it I thought it was kinda loud and almost went out and bought a Donaldson muffler to replace the MBRP offering. Then, after a coupla weeks I really grew to love the sound from the MBRP setup.

Cheers!

Mike

 

I just put on a diamond eye 4" including the flow thru muffler

I really like it, sounds great