GM Truck Club Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter #1
Hey,

i need some help choosing the correct size for my cat back system. i have a 11 silverado 5.3. if i run (1in/2out)cat back duel 2.5in pipes will i lose a lot of back pressure and low end? or is it fine for the 5.3L?

whats the pros/cons for running 2.25/2.5 for the 5.3L. i will be running the magnaflow XL(14" body muff).

i dont want to lose any low end torque.

i also will be running a CAI just FYI.

Thanks for any and all help.
 

·
Registered
Joined
·
7,291 Posts
Unless you plan on installing a cam and head work, then the 2.25 is fine.
 

·
Registered
Joined
·
7,291 Posts
Not really a sound differance. Exhaust systems are like camshafts, bigger is not always better.
 

·
Registered
Joined
·
240 Posts
For your 200-400hp motors, dual 2.25 is about optimal. From my understanding 3inch single or equivalent cubic volume is what your shooting for. A properly tuned exhaust wants to keep the gases moving quickly which means you need the gases to stay hot. Too large a pipe causes the gases to cool and expand which collapses the exhaust pulse waves leading to loss power.
 

·
Registered
Joined
·
7,291 Posts
I know Flowmaster use to have a exhaust sizing chart on there website. You may want to check and see if they still have it.
 

·
Registered
Joined
·
240 Posts

·
Registered
Joined
·
240 Posts
It simply shows HP to Pipe size correlation.

2.5inch dual exhaust will let you go 500+ HP
2.25 dual exhaust will let you go up to 415HP
2.0 dual exhaust will let you go up to 328HP
3.0 single exhaust will let you go up to 370HP

Now these numbers do not account for muffler resistance, or length of pipe, but it should give you a rough estimate.


To sum it all up: Just go with dual 2.25" pipe if you can. 2.5" pipe will most likely cause a bit of low end torque loss.
 

·
Registered
Joined
·
992 Posts
1 - 11 of 11 Posts
Top