Dual exhaust systems from extractors back....

What % gains or loss, assuming both are using hi-flo muffler & cat with same size pipes would a dual system have over a single system other than horny looks?

If you where to split the system down the middle after the extractors then would'nt that be like running a five inch single pipe in terms of throughput, and you would'nt need anything like that unless your running a turbo, or otherwise you might lose power. :cry:

I am sure someone will correct me if I am wrong though. :p

That's exactly why i'm asking the question :-)

I have a K&N panel filter at the moment, but want to get the exhaust system well and truely sorted so that I can take full advantage of any future intake mods (CAI with POD filter, TB etc etc).

And as everyone knows the main difference in power figures from the VR-X over an Exec is in the exhaust system which gives it those few extra horses!

I'm sure nobody will correct you :)

on a turbo it would definitely be good, u could have very high equivalent to 4 inch or more in flow without the horrible drone that comes with anything bigger than 3 inch single systems.
but on a N/A i think it could still work well. u need to be careful not to lose backpressure too much or u lose bottom end power,
u need pipes tuned length in the primaries and secondaries that is a bit harder to achieve on an engine mounted east west than an engine north south where everything is identical on both sides. u would have smaller mufflers and probably no centre muffler with the cats being adequate.
I had a twin system done on a 302 (4.9 L) Fairlane i built up a long time ago. it performed and sounded fantastic. there were only 2 fairly small mufflers, one on each side, and piping was about 2inch. I think if you went with a similar design and piping of maybe 1.5 inch it would fit nicely, not add extra weight and perform and sound awesom.

many years ago hdt and ford did tests on their exhausts systems and got better out of 1 large pipe than 2 smaller pipes as there is a lot more surface area in the 2 pipes thus more back pressure or drag, which ever way you look at it.
Although area is increased so is the drag.

u need pipes tuned length in the primaries and secondaries

I reckon you'd only need tuned length primaries as the secondaries aren't merging.

I'd only ever go a split system on an 8 as the 6 is an odd number for firing cycle and you might not get as much scavaging happening compared to an 8.

i got twins on mine.. split about the rear axle... i can't really tell if there was much power loss... maybe very slightly, but mines slow anyway..

the sound is awesome! but that could have something to do with the turbosmart cannons hanging off the back.

i think mitsiman looked into doing a twin system the whole length but found out there wasn't enough room, and maybe settled on something like this as there would still be an increase in flow?? i'm not 100% sure... i guess he'll have to enlighten us.

i highlighted the cannons coz they're fairly well hidden under the bumper and didn't show up in the photo. i've had cops follow me fairly often and not one has said anything... (including the cop on his bike that just about fell off at the lights trying to look under!)

«Å§¥LüM»,
How much did that system cost you? ... looks sweet!

i bought both mufflers from autobarn for $290 each... then the piping work cost about $250 so a total of early $900.... yeah i should have gotten headers instead but i just love the look of it 2!

i'll stick a snip of the up coming FAQ....
[quote:1e7fd74b32]
4. I want to upgrade to a twin system, what sizes are best?
For a twin Cat back system 1¾” is plenty big enough… probably too big… remember if you have an oversize exhaust you will loose torque down low! (its a back pressure related thing)

the proportion of the air flow rate to pipe size, is roughly
air flow rate = (C x pipe diameter)² ...... (where C is some air flow constant)

Ie: if you have a 1” pipe you have a flow rate of 1²xC, if you have a 2” pipe you have a flow rate of 2²xC = 4C, if you have a 2½” pipe you have a flow rate of 6.25C. get the picture?
Now the as the stock system has a 2¼ system (flow rate = 5.06C) you will want a twin system with about the same rate… so 1¾ is roughly the same (2 by 3.06C) as the 2¼ system at 5C

If you want a true twin system (i.e. split from the extractors back, you’ll need to talk to your local exhaust specialist. But the above information still holds for how big you’ll need the pipe
[/quote:1e7fd74b32] also if anybody has issues with this let me know... we will be giving a full preview of the FAQ before they go up to clear any bugs.. pm KB if you want to ad something, or either of us if you have drama's with the content.

i got twins on mine.. split about the rear axle... i can't really tell if there was much power loss... maybe very slightly, but mines slow anyway..

...bla bla....

i highlighted the cannons coz they're fairly well hidden under the bumper and didn't show up in the photo. i've had cops follow me fairly often and not one has said anything... (including the cop on his bike that just about fell off at the lights trying to look under!)that looks sweet! but you said its not split from the cat back right? have you any pics from underneath???

i bought both mufflers from autobarn for $290 each... then the piping work cost about $250 so a total of early $900.... yeah i should have gotten headers instead but i just love the look of it 2!

You should get the headers aswell, not instead of the mufflers. ;-)

Looks & Performance!!!

[quote:ed3e00a868="«Å§¥LüM»"]i bought both mufflers from autobarn for $290 each... then the piping work cost about $250 so a total of early $900.... yeah i should have gotten headers instead but i just love the look of it 2!

You should get the headers aswell, not instead of the mufflers. ;-)

Looks & Performance!!![/quote:ed3e00a868]
i think he was meaning he only had x amount of $$ to play with... they'll come in time

sorry, no pics from underneath, i havent had it up on stands since.. i'll try to remember sometime


dont worry akko, i'm just about finished with looks.. performance is next on the list!

that asylum does look insane! on modern cars the cat is the most restricted part of the system, so a twin system with 2 cats to double the flow would have to be better im thinking, with the rest properly matched to not lose too much backpressure.
maybe its right though that a true twin all he way doesnt suit V6 bec of firing orders, would be good to find out!

thats the nicest twin system i have seen on a magna. subtle, but very nice. love the downwards angle they are on

yeah i didn't really want them to hang right out of the back, or have to modify the rear bumper, so when i seen those... i had 2 have em! i can't wait to do some decent mods to see whether there is a big performance difference... i have noticed that i'm not that quick off the line, but as soon as i hit 2500-3000 rpm it pulls VERY nicely... only other mod is the pod filter