Just wondering if it makes much of a difference to have a 3.5" downpipe as opposed to a 4". THe cheaper systems that I am finding on e-bay seem to use the 3.5 inch. However, in a trade off, one manufacturer uses 14 gauge steel instead of 16 guage steel, and it carries a lifetime warranty instead of the 1 year. (aluminized systems). This system (AFE I think) is at least $150 less than the MBRP. Is it worth the difference to go to 4"?

thanks

 

Unless you are planning on big HP, I don't think it makes much difference. They are both mandrel bent and are a huge improvement over the stock DP.

 

I will probably end up getting a chip from Jody eventually.

 

The 3.5" downpipe has an open area of 9.6 square inches, while the 4" downpipe has 33% more open area at 12.6 square inches in comparison.

Obviously, the 4" downpipe can therefore handle 33% more exhaust at the same friction loss (into the cat) in comparison to the 3.5" option.

 

Trent Fliginger,

We stock the AFE and the MBRP. The AFE has a section of 3.5 that is approx 12 inches long so it's not the whole down pipe that is 3.5. We have found that on a stock truck the 3.5 section helps improve bottom end torque. If you run up the HP above say 75-80 HP then a 4.0 is the way to go, but the small section of 3.5 doesn't hurt you at all even with the HP increase. Call us if you have any questions.

Mark @ DPPI

 

I went from the 3in stock down pipe to the 4in down pipe in search of lower EGTs. Some say that you loose a little low end, I didn't notice. I say go for the 4in.

 

Get the 4 inch dp and 5inch system from Mark R at MKO diesel.
You won't beat the sound!