Exhaust info on 95 K1500

[ryancross]

Hello,

I am wanting to perform an exhaust upgrade on my 95 K1500 Z71 with a 350 TBI. It has a 4L60 E and 3.42 gears. The tires are 30.7 inches tall. I need to run a cat where I am. My friend has done the following on an identical truck and has seen a 1.5mpg improvement in fuel economy in the city and has a good bit more power. He ran all new 2 1/4 pipes from the factory manifolds to flowmaster Y collector with 2.5 inlets and a 3 inch outlet. This runs straight into a 3 inch cat. A 3 inch pipe then runs from the cat to a Hooker Aerochamber single inlet dual outlet muffler. Inlet is 2.5 and outlets are 2.5 as well. He then has two separate 2 1/4 pipes each of which come off one outlet on the muffler and exit behind the rear wheels.

Does anyone think I could improve on this combo? For instance decreasing or increasing any of the diameters of the pipes, y collectors, cat and muffler. Any and all suggestions or discouragement are welcomed. Thank you for your time.

Ryan

 

[sweetk30]

good system proven to work. but why do 2.25 to 2.5 y pipe unit to 3" then back down to 2.5" ? ? ?

thats creating problems in flow. never step down if at all possible.

and 1 other thing to add is a set of bolt on shorty headers that take place of the manifolds. this will let you step up to 2.50 pipe from headers down.

good luck and you will see the power from this mod.

 

[ryancross]

Thanks for the reply

Hey...I appreciate the feedback. It did not make much sense to me either. Except when you take into account that those Y pipes only come in certain sizes. And that a 3 inch pipe has a good bit of flow and probably closer in cfm to 2 2 1/4 pipes at the same time. Plus...superchevy or chevyhiperformance has an article by David Vizard all about exhaust flow. All I know is that I wish I did not have a cat on there. I would run Mid length headers through 2 1/4 pipes into 2 1/4 Maxflows. The cat and y piping two into one makes it more tricky.

Ryan

 

[sweetk30]

good flowing y-pipe like we have talked here and high flow cat will basicly out perform duel system . and also the single i thing has better sound from the performance muffler also.

www.tbichips.com years ago did a dyno test on a bone stock exaust in a tbi 350 truck he picked up of a local swap sheet.

he chassie dyno'd it and then did the shorty bolt on headers / flowmaster y-pipe builder and 2.5" from headers to that. then single high flow cat and 3" muffler and 3" tail pipe. he got avg of 35 more hp at the rear wheels.

so it does work good for the system that it is. the stock exaust is just to tiny and restrictive. good luck on yours and post back up what happens and how you like it . mabye even some pictures also when done .