I need to get an exhaust for my 2004.5 Duramax. Any opinions on what I should look into

 

I really liked the Magnaflow kit i helped install on an 01 LB7, it fit nice and sounds awesome, and it was cheaper than most other kits

Mbrp is a nice system but your going to pay a little more for it

 

MBRP

 

MBRP Duals.

Rear view.



Driver side view.



Crappy passenger side view.

 

if money is no object go with banks duels. if money is tight, find your self a cheap mom and pop muffler shop and have them cut out your muffler and cat, and weld in 3.5 inch pipeing. it litterally is just like having a 4 inch. the difference is so minor that you would never tell the difference between 3.5 and 4 inch

 

I would never give Banks any of my money.

if your mechanically inclined get a piece of 3.5" flex pipe about 2" long, and a few good clamps, and you can cut out the stock muffler and cat and have a straight piped system, thats what I have right now

if you do the math 1/2" might not sound like much but lets take a piece of pipe 180"(15') long as an example
3.5" pipe
A=PI x Rsq
PI x 1.75"sq = 9.62"sq x 180" = 1731.6 " cubed

4" pipe
Pi x 2"sq = 12.57 x 180" = 2262.6" cubed...

So thats a difference of 531" cubed that a 4" pipe will give over 3", as well there is almost 2" increase in cross-sectional area, and thats not allowing for the kinks and restrictions in the stock exhaust

 

To each thier own, i like banks, but hey thats just me, as for the flex pipe, yeah you could do that, but me personally i like regular pipe just welded in. its looks better. and bravo on the math lesson, but as convincing as the numbers are, when its put into practice, it surprising dont make a whole heck of a alot of difference. Literally 3.5 vs 4 does not make any noticible performance or sound difference. only real diff is that 4 inch looks alittle better, but even still its nothing majorly noticible, especially if you do it right and throw a 3.5 inch to 4 inch tip on the end, but i would cut the stock exhaust back so that the tip doesnt stick out and look goofy. (o EGT my drop slightly with a 4 vs 3.5)

 

We have excellent luck with Diamond Eye.

 

Try Exhalt Motor Sports. I bought and installed a 5'' Stainless single side MagnaFlo on my 04.5 GMC for less than 600$. Every muffler shop around here wanted 600+ just to order then the a-holes wanted 150-200$ to install. Ordered, installed myself. The hardest part was getting the factory crap off. This system is from the front or down pipe back. It has been on about 2months NO CODES. Good Luck.

 

Silverline 4in duals.