Is it Taboo?

[Smokey Eddy]

Is it taboo to not have an exhaust at all and just point it in the general backwards direction. Have a downpipe that just leads to the underside of the car, goes back maybe 6 inches under the floor and then that's it...
If you don't mind the smell of diesel are there any ramifications that anyone can think of other than a sooty undercoat?
Maybe cut the end of the pipe so it directs the exhaust downwards onto the pavement
This is just a rediculous idea because mine is rattling SO much i just want to cut it off  infront of the cat.

im making a new one anyways but id be driving like this for at least a month if i cut it off before i had the new one ready to go on (because i have to match it to the new head im getting)

[cyrus #1]

I don't think it would be a great idea if you've got a rustbucket with holes in the floor.  Other than that I don't see any major problems as long as you don't have emissions testing.  I'm seriously considering going with a electric cutout on mine to dump just after the downpipe or running the entire exhaust.

[Smokey Eddy]

Right right.
We have emisions control here but that's not until i'll have the new legal length straight pipe on, and when i go get tested i'll just turn the fuel screw in as far as it will go without stalling and see how little smoke i make.

they just test opacity of the exhaust with a light. Foolish test for anyone who knows that a mechanical fuel pump is. And i'd run the boost into the exhaust possibly on like a second exaust mani i'd keep just for air care.

take the normal one off, put on the other one that has a line into it from the intake side with a 1 way valve set to like 5psi or something so it just blasts straight air through it.
UNLESS the psi set that low would cause a lot of unburnt diesel to come out under load. I think I'll just stick to turning the fuel screw down as far as it can go

[burn_your_money]

I have a friend who has a gutted interior in his MK1 TD and it's open downpipe. It's not too loud, but he says it's awful on the highway. He even has the HVAC junk removed so there is a huge hole right on top of it.

I'd carry a fire extinguisher (I do anyways) just in case the undercoating goes up in flames.

[ezekiel]

^^ truth

at most, you'll catch the undercoating in fire, but diesel is also colder than gas exhaust.  It's really unlikely anything would come of it.

but I also bet it'd drone like hell at speed.

[53 willys]

I wouldn't do it..you will be able to smell your soot stained car from across the parking lot!
we have 4cyl deutz diesel's at my work and when the exhaust leaks and nobody fixes it it pretty much ruins the under carriage and stains them with soot and stink...after so long cleaning and soaping it is a waste of time and you end up with one stinky car.
it's like driving a cold Perkins diesel ALL the time :shock:

[commuter boy]

If the car originally came with a cat, if they don't see one at Aircare it's an automatic fail, they won't even do the emissions test.

If the exhaust doesn't go all the way to the back, or out the side, they can't hook up their opacity sniffer, get pissy and can fail you too.

Run a straight pipe all the way to the back.

I've got an AAZ with a PP 2.5" downpipe, a 2.5" straight through muffler and it's still a bit loud in the cabin for conversation, I'm probably going to drop a resonator into the mix at some point to quiet it down more.

[spencebm]

i have been running just a 3 inch down pipe for about 4 months with no problems in my jetta and its not too loud.  if you get it under the car and pointed to the ground then it will be fine.  just make sure it isn't near anything that can't get hot!!

[foxracer1]

The soot will destroy your car underneath. Sounds good but drones alot on the highway.

[spencebm]

Well depends on how much it smokes but mine really doesn't drone at all on the highway in the Jetta.  Tom is a girl

[Smokey Eddy]

Hahahahha I love the banter!

I've decided to cut the muffler off so i can keep the cat and just slide it in there for air care. Both the muffler and cat buzz like nuts against the bottom of the car which i know isn't good at all but i haven't gotten around to fixing it and i've gone through hell with that exhaust - welding new pipe where it goes over the rear cross member; repairing holes with pop cans; picking it up off the road, putting it through the rear windows and welding it back on at school.

Here's what im thinking
for normal driving
DP=============|~~~~
for air care!
DP=== CAT =========|~~~~~~
I'll just have some method of pulling a middle chunk out of the line and replacing it with the old cat. Hopefully the new pipe will be super shiny (maybe i'll paint it with "Alluminum" high temp paint)  for the sole purpose of making it obvious that people don't really follow air care regulations when they look at my exhaust and see a disgusting derelict catalytic convert. in amongst the shiny nice looking straight pipe.
"Uhhhh, is that always there?"
"of course it is sir! It's all about the enviroment after all. Even though i'm pretty sure that cat doesn't do ANYTHING anymore, but it looks like one right!"

Does anyone have funny stories of emissions control where they turn the fuel screw down to zilch and get like a reading of 10% of the max allowable or anything funny like that?

[79rabbit4dr]

Here's what im thinking
for normal driving
DP=============|~~~~
for air care!
DP=== CAT =========|~~~~~~

I'm so glad we don't have testing here in Idaho, Washington was waaay too strict about it when I lived there. I agree with others about not leaving it to dump out under the car for too long, at least dump it out the side. But if you're planning on having it full length within a month, it's fine. I'm looking forward to straight piping mine here soon.

Oh, and with the removable CAT design, just make sure you're not disrupting the flow of the exhaust too much (as in expanding/contracting diameter), otherwise you'll loose a little of that potential power gain.