how much louder is a o2dump w/open downpipe vs o2dump w/ straight pipe?

[ryu]

well im running no muffler right now and i dont mind the truck sound at all. im still on the stock piping w/a cat tho. i know im going w/o2 dump but wasnt sure if i should get a 2.5 straight pipe that goes to the back of my car (no cat or muffler) or if i can just bolt on the stock downpipe onto the o2 dump and say screw the piping to the back of the car.
is the difference in sound big?

 

[EclipseOwner95]

The o2 dump makes the same amount of noise whether you have open downpipe, or full exhaust, the same amount of exhaust is going to come out of the wg regardless, with open downpipe you just wont be able to hear it as much, with a full exhaust everything will be quieter, so the o2 dump will be more audible.

 

[DSMvroom]

well i mean if you are plannin on runnin 2.5" straight pipe no cat, might as well save yourself the trouble and don't attach anything after the o2 housing.

I'm sure the difference in sound would be significant if you did run the pipe to the back of the car, but still you would have no cat and no muffler.

Your end result is really loud, or really loud. I don't think you'd be able to tell too much difference either way, especially since you won't be able to do a side-by-side comparison.

 

[91PlyLaser]

you shouldnt worry about how loud your exhaust is going to be. you should worry about performance your exhaust is going to add. I would suggest getting a atleast 2.5 inch turboback before you decide you want to dump. IMO

 

[K_Hill]

I agree with him ^^^^^^

 

[ryu]

well performance is the reason i want to takethe whole exhaust system out. i just dont want it to be too loud. im going w/the evo16g and o2 dump so i wont have to worry about boost creep. stock open downpipe on a o2 dump cant be restrictive can it???

 

[SethA]

well performance is the reason i want to takethe whole exhaust system out. i just dont want it to be too loud. im going w/the evo16g and o2 dump so i wont have to worry about boost creep. stock open downpipe on a o2 dump cant be restrictive can it???

Just dumping will not guarantee that you will not get creep. You will probably need some porting too. Oldman has posted what porting is necessary several times. The stock downpipe will be slightly restrictive even if it is open. For maximum performance a mandrel bent downpipe would be better. Any open down pipe is going to be very loud.

Seth

 

[99gst_racer]

well performance is the reason i want to takethe whole exhaust system out. i just dont want it to be too loud. im going w/the evo16g and o2 dump so i wont have to worry about boost creep. stock open downpipe on a o2 dump cant be restrictive can it???

If you remove just the muffler and retain the stock downpipe and cat, then you aren't gaining much performance at all if any....

If you remove the entire exhaust system and dont port the turbine housing, you will get extreme creep. And an O2 dump will not cure that.

It's a trade off. If you want performance and you remove all restriction in the exhaust, you will creep (unless you do the turbo porting). And if you dont port and you're not creeping, then you probably have unwanted exhaust restriction.

 

[95AWD_TSI_TALON]

Another thing about running open O2 and all. I sold my 3" turbo back and was in the middle of having a friend make my 3.5" turbo back. We fabricated the entire o2 housing and tig'ed up the flex section so it dumped just after the oil pan (is my DD and ran out of time that day). Loud isn't the only issue its all so exhaust fumes and smell you have to worry about coming up into the car and yes they do make you drowsy! Creep is held back by restriction...no restriction equals creep without proper set up - porting AND or external wastegate.
Matthew

 

[GST-RIDER 95]

Loud isn't the only issue its all so exhaust fumes and smell you have to worry about coming up into the car and yes they do make you drowsy!
Matthew

I got a full 3" turbo-back and ext. dump no cat...
Loud can't start to describe the growl coming out of my beast I love it. BUT the stench of smog fumes give me real heavy head ache after I've been driving for a while.
Now I question my self if this feature should be left for track vehicles only. In other words is my own health worth the extra excitement

I don't mean to hi-jack or intrude but does routing the fumes any other way than straight down take away from the efficiency of the dump?

 

[ryu]

how bad are the fumes? is it really that bad? are you talking about open downpipe or just o2 dump? because the o2 dump isnt open when your at idle right?

 

[95AWD_TSI_TALON]

BUT the stench of smog fumes give me real heavy head ache after I've been driving for a while.
Now I question my self if this feature should be left for track vehicles only. In other words is my own health worth the extra excitement

I don't mean to hi-jack or intrude but does routing the fumes any other way than straight down take away from the efficiency of the dump?

GST-RIDER - it sounds like you are just running rich. I have been driving with an external dump for almost 2 years now. I only had problems when coming back from the track exhaust less or when I drove around with half an exhaust do to making it. I have noticed when I rest my ecu and it goes back to my standard tune ( is richer) I get the same issue you are talking about. I would get a wide band/ and tune down a little. Should stop the symptom you are having.
Matthew

 

[95AWD_TSI_TALON]

how bad are the fumes? is it really that bad? are you talking about open downpipe or just o2 dump? because the o2 dump isnt open when your at idle right?

We are referring to open DP. If your car is not well tuned and running rich it can be BRUTAL. But you wastegate will only open under boost at the set psi by your boost controller.
Matthew

 

[ryu]

im just gonna go w/ o2 dump w/3" straight pipe minus muffler. thanks for the info guys

 

[GST-RIDER 95]

GST-RIDER - it sounds like you are just running rich. I have been driving with an external dump for almost 2 years now.



I get the same issue you are talking about. I would get a wide band/ and tune down a little. Should stop the symptom you are having.
Matthew

I drive about160mi a day at cruising speeds and in the most part I get sick after driving maybe the first 40-50mi. (from my house to Los Angeles more or less.)

You got a valid point and got me there
I was in the process of tunning my car when I blew the head.

 

[MNGSX]

I run a 3" turbo back on a PTE 56 trim and I dont creep...

Its more than just the turbo back but what turbine housing and wheel... in addition to where you set boost...

I burn 106 octane mostly (85% alcohol) going to the supermarket or on cruise on the hwy... So umm what is this low boost thing people talk about...

I'm thinking of swaping to a ported and hand polished bullseye turbine housing eventually and making a "wastegate-back"... Probably tack weld it to the turbo back to hang it and go thru the same muffler body with a perf tube core... I'm getting good at TIG welding and want to show off is part of it...

 

[95blackGsTurbo]

I don't see the point in running open downpipe at all. For 95% of people that do it, they don't make near the power that running that open of an exhuast requires. It carbons up the bottom of the car and smells pretty bad at times. I can't even see running an exhaust with no muffler. There is virtually no performance gain from it and around here there are some Honda guys and whatnot that drive around with no mufflers and even at very low throttle it's annoying as crap at 2 a.m. and sometimes it wakes me up in the middle of the night so I run a full 3" mandrel bent with cat and open o2 with a muffler for the simple fact I would be pissed at me if I got woken up by someone's loud exhaust.