Last night I ordered a set of long tube headers for my truck. I need some help with my exhaust. I want true duals and a H pipe. What size pipe should I use? What mufflers sound good? How should I route the pipe? Any help would be appreciated. Thanks

 

with long tubes your gonna either have to hack up the factory y-pipe or get a custom one.

im pretty sure 3'' is a good size for a single exhaust but for duals i would step down to 2.5'' so you have good back pressure,

what kinda of muffler are you gonna run? ive seen some that are dual in dual out and act as a x-pipe! im not sure what brand it was though, go check out summitracing.com youll find something good!

are you gonna run a high flow cat or no cat?

right now all i have is pacesetter shorty headers and a flowmaster knock off muffler and it sounds good even with the factory y-pipe/clogged cat

 

I am going to run 2 highflow cats and will not have a Y pipe because I want true duals. Just dont know what mufflers, glasspacks of flows or what?

 

make it easy, buy a magna-flow true x muffler..

you don't want ANY back pressure.. back pressure is bad, period.. you want it small enough diameter though, that it heats up.. Heat promotes scavenging.. scavenging is good, period..

2.5 is fine, as it will still open up enough to breathe unless you have some silly mod's going on such as ported heads and ridiculous cam..

I highly rec. the dual exhaust as you've described, with either H or X, through good bends and LT headers.. I don't have LT's, but that is likely to change soon enough.. Just getting rid of the factory Y is going to open that exhaust up tremendously, and eliminate the back pressure you're currently generating, while not adversely effecting scavenging..

 

is that the muffler with the x pipe in it?
I do have heads for it and will be buying a cam for it.
http://www.compperformancegroupstore...=LACAMRFHRXECC
The exhaust shop said to do 2 1/4 from the headers back to the mufflers then to 2 1/2 out to the 4 inch tips. Does that sound right to you? I am thinking eather two 8 inch cherry bomb glass packs or 2 flowmaster 10 mufflers. But dont know.

 

2.25 is fine too so long as the bends aren't too abrupt.. I wouldn't go any smaller though, especially with that cam and ported heads.. you'll generate enough heat to get a good conveyor of puffs passing through it, but not so open that the air cools too quickly and slows, creating a barrier for the next pulse to pass through (which would be back pressure)..

the magna flow true x is what I run.. that rascal is HUGE.. I swear though, you could drop a baseball THROUGH it.. and the sound is great too.. you won't need anything else after that.

I also run magna flow high flows.. they are crammed up in the same area the OE big ol' cat came from..

I'm assuming you're running a federal emmisioned truck, and you'll play hell with your o2 sensor (upwind).. I have a cali w/ 4 cats on it, and 4 o2's so mine was simple.. You'll be needing both banks monitored, which can be an issue because if it is monitored too far back it is an issue, and if it doesn't monitor both banks it can be an issue..

though I love the true-x muffler, you may be better off with an x in the place of and replacing the y now that I think of it.. you'll need an o2 bung in the H or X..

 

I only have one o2 sensor so I could just put it in the center of the X or H right

 

yup, and you'll want it as close to the heads as possible, which kinda eliminates the need for a true x muffler, as you'll already be connected.

 

When I was talking to the guy at the exhaust shop he said If I went with 2.5 all the way back I would drop some of my bottom end is the true?

 

then he needs to study exhaust theory..

the basic concept is generating enough heat to create a vacuum like effect from the heads to the tips- the engine is only strong enough to push it so far- it needs help from heat to create that vacuum, and help from the other bank to generate a tug when the opposite one slows.. It is referred to as scavenging, but many confuse the term with back-pressure.. back pressure is bad.. scavenging is good..

on the flip side, if it is too open, the air cools too fast and creates a barrier for the pulse behind it.. back pressure..

if it is too restrictive, it can't get out of the way of itself fast enough.. back pressure..

just the right size will heat enough to create that conveyor I mentioned, and NOT create back pressure..

you're leaving cats in it- that actually will help you because cats get dang hot.. dang hot when the exhaust is attempting to cool, which gives you a tug about the same time the engines pushing has exhausted itself..

you're on the right track, and he is right but not for the right reason- smaller pipes generate more heat.. wrapped pipes not only keep the engine bay cooler (which is a side effect of wrapping them) they also insulate and keep the pipes hotter (which is good).. ceramic is the preferred wrap, but exhaust tape is often used as well.