Twin vs Single system

[finch]

E30s some stock with twin pipes all the way along.
is it advisable sticking with this? would it make any differance at all?

i have a single 2.5" with stock headers and it sounds like shit :(

getting custom extractors soon. worth changing to twin pipes?

[nando]

it might sound better..

I had single exhaust on a 6 cylinder once, sounded like poo. but that was an all original '67 runing on 4 cylinders (and it could still burn off the rear tires!). dunno what a single pipe M20 sounds like.

I'm planning on going dual 2" to my muffler. nothing too special for now, just need to replace my old cat and cracked factory downpipe.

[Tangent]

Never having heard it side by side with a stock exhaust 325 I wonder what mine sounds like by comparison? The stock setup has a dual in/out cat doesn't it? Mine was replaced by the previous owner so I've got dual pipes to a y-pipe intoa larger diameter cat, then another y after the cat into the stock dual pipes.

[808BMW]

The stock setup has a dual in/out cat doesn't it?

Yes.

[finch]

got other car problems atm

headers/exhaust will have to wait.

[Gus]

my mate has a single 2 1/4 on his 325......sounds good, a little bit raspy but still deep so is all good.....only has one resonator and then rear muffler.....

ive got headers going to twin 2" with long resonators, one each pipe going into an e36 Racing dynamics rear muffler...i really like the sound.....quite quiet no drone but good when ya gunning it

as long as doesnt drone, all good

[Tangent]

So the 325 should have resonators? Mine goes manifolds -> downpipes -> y-pipe -> cat -> y-pipe -> twin pipes -> 2 in/out muffler.

[finch]

as long as doesnt drone, all good

mine drones like crazy.. :?

I think twin 2" is the way to go.

[BahnE30]

2 inch dual all the way back into twin dynomax truck mufflers with quad tips, on an eta. looks like it makes power but it really doesn't
lmao

[cheades]

I had a single setup on my m20 and it sounded good, weighed about 30+ lbs less than stock as well. Did 2.5" with a high flow cat and a dynamax muffler, pretty quiet but loud enough when on the throttle.

[finch]

what do headers do to the note? louder? less drone?

[mspiegle]

regarding the subject...

A single pipe setup has the potential to give more top end hp if sized properly. This is beacuse exhaust gasses need optimal escape velocity for scavenging effects. If you look at a cross section of pipe with gas flowing through it, the gas in the center moves faster than the gas on the outside of the pipe. This is because the gas molecules will hit/rub against the tubing and slow down.

benefits to single-pipe? simpler, cheaper, lighter, more top-end power.

benefits to dual-pipe? doesn't sit as low as a single pipe would. Usually gives more low/mid hp. allows for an even larger exhaust diameter (you couldn't fit a single pipe under the car that woudl flow more than a dual 3")

[JRKOUPE]

I had a single setup on my m20 and it sounded good, weighed about 30+ lbs less than stock as well. Did 2.5" with a high flow cat and a dynamax muffler, pretty quiet but loud enough when on the throttle.

where did you y pipe it?.... before cat or after?.

[nefarious7907]

are you kidding me dual 3" on a 2.5 or 2.7 liter engine. thats such a waste of time money contemplating something like that. most fireturds have single up to the muffler and rustangs half true dual but it's 2 1/2 90% of the time, 4.6,5.0,5.7 lt engines dont even need dual 3 inch to sound good and perform. Other than that a few turbo ricers have 3" single exhaust for their cars because they are just trying to get air out, and need zero backpressure.

[Gus]

i had to get a custom exhaust made up for new car as old one didnt fit..went from dual 2" from headers back with rear RD muffler and 2 resonators, to a single 2.5" from headers with one resonator and one muffler...actually noticed a little increase in power (bum dyno of course..nothing to back that up) from the duals....also much cheaper (half as much steel)