trust

My 01 QC still has the original exhaust on it, I think it's 2.5" tubing, and it is still in good shape, however, I have been told by both vendors and friends that if I go to a 4" system I'll pick up a couple more mpg and have better performance as well. I know that is a universal claim and for those with extensive power mods I could see perhaps an increase in pipe diameter but on an otherwise stock engine? I dont want it nosier either so I wouldnt be interested in a straight through system.

If this is truly a benefit is there a kit that seems superior or just go to my friendly local exhaust shop and have them bend up a system? Particular muffler?

Thanks!

Busboy

The factory exhaust on the 01 is a 3 inch and if my memory serves me it is good for up to 350HP, save your money.

nkennedy

I've heard & read the same thing. You might lower your EGT's a bit with a straight thru 4 inch, but not much performance gain over the stock.

Midnite

I still have the stock exhaust in my 2000 truck, except I replaced the muffler with the replacement pipe from Geno's Garage (I kept the stock resonator). My EGTs dropped by about 50 deg. cruising empty and about 200 degree full throttle empty going up a 10% grade.

A good 4" exhaust with a straight through muffler should get you about the same. I agree about HP and mileage gains--I didn't notice any difference.

SIXSLUG

You will see a slightly lower egt temp with a 4", but realistically, the turbo outlet is around 2.5 inches so anything larger than that on a stock engine and you will be ok.

As stated the factory pipe is 3", Cummins spec'd a 4" so Dodge put a 4 inch flare on the tailpipe to save some money.

I didn't feel or notice or record any improvements over stock, just growly and a little louder.

Diesel Dave2

I seen the same result as Kurt mentioned....

j-fox

There are some who claim a LOSS in mpg with bigger pipes!!
the turbo is by far the most restriction in the exhaust.
Vendors will claim this and that because they make money off of the sale.
Friends claim wonderful improvements too to justify the $$

For stock or smild power changes the 3" is fine.
A larger pipe can let the gasses expand to quickly and loose velocity.

But, if you plan to add injectors or boxes, and need to replace what you have now, plan ahead and go 4".

Do NOT go to a muffler shop because they crimp the pipe at bends and make it a restriction!!!! You want mandrel bent pipe like most all aftermarket pipes are.


BTW, I just had my top charger off to tighten the manifold bolts and did a 15 minute port+ polish on the turbine side. It has noticably improved the spool up.

rebal

the only thing i saw was a nice deeper tone nothing else

trust

Excellent guys, thank a bunch! I always struggle to separate the truth from the fiction when it comes to this sort of thing and generally find myself not satisfied with the results. Sounds like y'all saved me that frustration this time. Thanks!!

rickf

This was good info as I was also wondering. I have been racing for years but with gas engines and the same thing applies there. You can go to big and hurt power since you lose the flow and it tends to swirl and back up. Problem is where do you buy a decent 3" system? I was looking at a Diamond Eye 4" system because the price was reasonable. Who has found the best prices and where?

Rick

nkennedy

Other thing that stops me is the original is stainless steel, and the replacement SS unit is expensive.

HOHN

I have had the stock exhaust on my truck for 10 years.

I've been running biggish injectors for 9 of those.

I have never found a need for a larger exhaust with the stock turbo and manifold.

A full 4" is really only valuable when you go much bigger on the turbo.

outlaw13

but it sounds soooo nice eith a big pipe don't it???????

KATOOM

When you're towing pulling a grade and your exhaust is "freight training", your exhaust could use a little more free flow. You want the exhaust to flow out well but not with the velocity of a water hose. The stock 3" straight piped, which is really 2.5" because its not mandrel bent, will flow almost the same as a 4" mandrel bent with a sizable muffler. As mentioned, a cleaner lower tone exhaust while still achieving optimal EGT's is the biggest reason for a 4" exhaust w/muffler. I straight piped my stock exhaust to help keep EGT's in check while towing. It helped but the noise is sharp, high pitched, drones around 2000 rpm, and is just way to loud. I actually strapped a piece of metal to the exhaust pipe where the muffler and resonator were to reduce the drone. It helped considerably with getting rid of the drone but its still to loud. I want a 4" w/muffler.

trust

Excellent stuff guys, thanks again, I am SO glad I asked, that $$$ can stay safely tucked away in my wallet to look for a new door....

I wish I could get this quality feed back on jeep stuff