Cascade Crew

[pathology knight]

well i'm getting close to needed some exhaust work and i'm not really sure what to do.

i just put on some new headers and my mechanic says i needs a few parts to connect it to the stock pipes. things like a Y-pipe (2 to 1) and a flange reducer thing (summit # 10110FLT).

i'm wondering if it'd be better to get the whole thing redone? it doesn't need to be done, nothings broke or rusted or anything, but if i have to by all this extra crap, would it be easier to take the stock stuff off and just get an all new 3" set up?

also, should i do a dual set up? dual pipes in to one muffler with 2 out-pipes? two mufflers? what kind of mufflers?

help!

[305 302eater]

It depends on how much power you are/want to be running. I have a 3" flowmaster cat back exhaust on my Iroc and it seems to be fine for power and sounds great.

[pathology knight]

a little extra power would be fine, but i don't want it to sound like crap.

i good "v8" sound with some get-up-&-go would be just fine.

is yours just a single pipe to the muffler and then 2 outputs?
stock, mine is like that but i don't know exactly what to do.

what kind of flowmaster?

[91RSVert]

I have had all mine from the motor to the tips done in the past 2 months, in 2 different sections. Cat-forward. Then Cat-back.

Cat-forward was done w/headers and no cat(didnt have one in stock). I ran (2)2.25 pipes tell they meet. Then 3" back. Choked down to 2.5" at the cat. I had a removeable dump installed where the cat should be. The car flowed the same with dump open, or dump closed. I dont think the 2.5 was a choke.

Ordered cat, it came in.

Had cat put on, and 3" back to muffler. This choked it back down. But honestly, I think its the cat. I dont know if the 3.0 back section was really needed for the mild flow motor I have.

Once it warms up, I'm redoing the setup so I can put the dump n test pipe back in. Honestly, I now have close to 800 in my exhaust. I dont think it was worth it.

A single in, single out usually flows better then a single in, dual out. But its also do you want to see the pipes? How do you want that all routed, etc.

[pathology knight]

i like the dual look, but i've heard one in, one out is better.

how much better? can you really tell a difference?

i've seen they sell kits for this. anyone know which place would be a good one to get? (quality and price)

i basically need from the headers back. i just put on a high flow cat, but it's a 2.5" (stock) i think. if i go 3" all the way, this does me no good.
i might have to try and sell it.
anyone interested?

[91RSVert]

There are 2 kits, plus a cat and you could have a full DIY exhaust from motor to tips.

IMO, 3" is not needed unless you have alot of motor work done. Heads, cam, ported intake, etc etc.

My orginal setup was manifolds, and a crushed 2.25 y-pipe. So anything was better then it.

[blue89]

This has been posted somewhere before... Just can't remember.

I'm running single 3 all the way with single 3 dual 2.5 out. Sounds good. No reason to go true duals unless your making, i dunno, 400hp? Complexity and weight outweight the benefits of true duals unless you need it.

If I were you, I would make the mechanic fab up the headers to stock cat. Then when you have time, do the cat back. Similar to what 91vert did.

[pathology knight]

alright, i could probably do that.

my engine mostly stock...nothing really high performance, that's good to hear that 3" really isn't needed.

[rjmcgee]

If you buy a cat back go with 3".

Even a stock engine benefits from breathing better, plus it won't become a restriction in the future if you decide to do some performance modifications.

[blue89]

Word

[pathology knight]

the guy doing the exhaust said not to run 3" due to the lack of back pressure. my engine's pretty mild, so he said it wouldn't benefit anything.

i found out the Midas put a new 3" high flow cat on my stock 2.5" pipe.
wtf?

Mr. Exhaust said that running 2.5" from the headers to the cat would be fine, and if i wanted (later) i could do 3" cat-back.

i'm thinking of getting a new cat that's the right size.
what do you guys think?

[Schultzy89GTA]

Personally, I wouldn't worry about the 3" cat.

-Schultzy

[blue89]

I suppose 2.5" will work. He probably doesn't want to route 3" over the axle! Try to push for mandrel bent tubing though. Some of the crinkle wall 2.5" can get really crushed on the bends.

I would tend to believe that everything after the cat would be mute. The change in density of the platinum honeycomb in the cat should be enough to reflect any pressure waves back up to the headers. So going bigger would just slow the gasses down and might provide less of a restriction. Maybe Dewey can chime in.

I'd say that the most critical part of the exhaust is from the headers to the cat. Just try to do the best job inbetween those two points and let the cat back just happen.

[pathology knight]

ok.
i don't plan on doing cat-back now because it's not really need, but headers-to-cat is a must do...i'm just trying to figure things out.

if you wouldn't worry abou the 3" cat, then i guess i wouldn't. i'm sure you know more abou these things than i do!

when i do replace the cat-back, i don't want to big of pipe where:
1. it's a pain
2. it's to much flow (or something) and doens't help any

i don't mind 2.5" pipe, but i want to make sure its running right and sounding good.

[blue89]

I told myself I wouldn't comment on the backpressure, so just read this:
http://www.thirdgen.org/techboard/exhaust/338421-more-than-you-ever.html

Sounds like your are on it. Does anyone have any pictures of a good cat up system? Jay?

[91RSVert]

All I had while my car was on the lift was my cell phone... n you saw them pics. Wish I would have thought later and taken the good camera

I could possibly get my car on some ramps saturday and snap some with the good camera. I'm not overly impressed with it though. Alot of things not done the way I wanted.

[mrpopo573]

Why is it every exhaust shop/dude warns us against 3 inch? Laziness is all I can come up with. They don't say anything against 3 inch on my fathers muscle cars or street rods, even when they are stock 350s.

My favorite excuse I heard was the guys at Kitsap Muffler. They told a kid with a Fox Body GT that 3 inch duals would hurt his bottom end.

[91RSVert]

Exhaust is mostly about the wave/pulse of the air. Some is heat also.

To small will obviously choke it.
To big will slow the pulse/wave down and hurt it.

Part of the pulse/wave, is heat. Cold air doesnt "move" as fast as hot air. So if it cools down to fast, it will cause some pressure.

then on the heat, is what material is it made of? This will also change the sound.


IMO, TRUE 3" duals on a mild/stock 302/351 would be to much. Now if he was all balls, or boosted. It would be good.

[mrpopo573]

Either way, it would not hurt the motor. 3 Inch is more than needed, but with one of the most aftermarket supported motors known to man, I'm sure you can find a reason to use the diameter.

[pathology knight]

so.....

this all these "physics" flying around what would be a good set up to have with a mostly stock 350?