Straight Through Exhaust

2.5 2.75 or 3" exhaust, which every u choose would it cause any problems short or long term by run it with no muffler or cat?

no problems, i don't like exhausts with no mufflers because it sounds like crap.

get a 2.5" with a decent muffler, you'll be happy

legally you should also put a catalytic converter in there, and maybe you'll have a resonator recommended to you by the exhaust installer.

but, its your choice and i aint being held liable if you break the law by not putting a catalytic converter in.

05' navara so legally not required to run a cat. i already have a beaudesert 2.75" system. it just very quiet (long straight through muffler) just wasnt sure what damage could occur if i removed the muffler and fitted a straight through pipe.

DOUG D22 said:

05' navara so legally not required to run a cat. i already have a beaudesert 2.75" system. it just very quiet (long straight through muffler) just wasnt sure what damage could occur if i removed the muffler and fitted a straight through pipe.

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I took my muffler off, and it didn't make much difference at all, still sounds like a hair dryer.

DOUG D22 said:

05' navara so legally not required to run a cat. i already have a beaudesert 2.75" system. it just very quiet (long straight through muffler) just wasnt sure what damage could occur if i removed the muffler and fitted a straight through pipe.

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all cars produced after 1975? must be fitted with a catalytic converter, even diesels...

who said that you dont have to?

EDIT: googled and have found a few different dates of when the law came into effect, but i've been told 1975?

i'm not sure what year it is, but my mate last year got pulled over and yellow stickered for not having a cat converter. after going over the pits his car was given the thumbs up for not having one and it was fine since his car was produced before that law came into effect.

maddogrc said:

all cars produced after 1975? must be fitted with a catalytic converter, even diesels...

who said that you dont have to?

EDIT: googled and have found a few different dates of when the law came into effect, but i've been told 1975?

i'm not sure what year it is, but my mate last year got pulled over and yellow stickered for not having a cat converter. after going over the pits his car was given the thumbs up for not having one and it was fine since his car was produced before that law came into effect.

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My '88 diesel doesn't have one and never did.

I thought cats started to get fitted around the late 80's when unleaded became the standard.
Didn't carbon canisters start around 73-75?

Catalytic converters were introduced on cars at the same time as Unleaded petrol, 1986. However, I do recall commercial vehicles having an exemption but I'm not sure if it still exists. Judging by the fact that all manufacturers are now fitting them I'd suggest not.

'98 diesel 75 series cruiser has one?

'08 diesel d22 navara has one?

surprised your '88 diesel doesnt have one pro-nav if as everyone is saying that they came in the 80's?

after a quick wikipedia search it turns out they were fitted in north america in mid 70's, guess thats where i got the 1975 thing from. also on the Midas website it says they were made compulsory in 1986. my bad about saying they were compulsory in mid 70's, wrong country, lol.

but as an '05 model vehicle i'm sure that it'd be compulsory to have one?

maddogrc said:

surprised your '88 diesel doesnt have one pro-nav if as everyone is saying that they came in the 80's?

but as an '05 model vehicle i'm sure that it'd be compulsory to have one?

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The '05 vehicle will require one. Diesels may have only got cats when they went to electronic injection? Early-mid nineties.

Pro-Nav2.7TDi said:

The '05 vehicle will require one. Diesels may have only got cats when they went to electronic injection? Early-mid nineties.

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any idea why such cars like the D40 have a cat plus the DPF?

did stricter emissions come in or something?

maddogrc said:

any idea why such cars like the D40 have a cat plus the DPF?

did stricter emissions come in or something?

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Yes. The two do different things. The DPF may be to comply with one of the Euro specs? Not sure, wikipedia will tell you.

The DPF is there to remove the black soot you see from the exhaust of diesels. It basically removes the physical dust from the exhaust so that there are no particles left in it.

The catalytic converter performs a chemical reaction on the gases of the exhaust to convert them to less dangerous ones.

Both can assist in burning unburnt fuel, completing the combustion process.

The objective of the combination is to ensure that diesel + air goes in one end, and CO2 + water comes out the other, eliminating carbon monoxide and other emissions.

It doesn't make the vehicle less dangerous in a garage (CO2 - carbon dioxide - can still kill) but the aim is for the vehicle to emit something that nature has a chance of removing (since trees all ingest CO2 to use the carbon in their growth cycle and emit the oxygen to the atmosphere).

I wonder why the Auto's have a DPF and the manual's don't?

The question was about straight through exhaust not about the legal requirement of cats..
So has any one just ran straight through and has/hasnt had problems?????

DOUG D22 said:

The question was about straight through exhaust not about the legal requirement of cats..
So has any one just ran straight through and has/hasnt had problems?????

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Yes i have done for many years on many different diesel engines, it produces way more power, not much more noise and a heap of whistle, never any engine related problems.

cheers mark.

My exhaust has a removable muffler that I can replace with a peice of 3 inch pipe. I have run it for probably 5000kms without the muffler. It feels slightly more powerful but it might just be in my head because it sounds tougher.

I have the muffler in atm because I don't like the sound at idle, it sounds tinny. I am going to try and get a resonator in the link pipe so hopefully I have the best of both.

mud4b said:

Yes i have done for many years on many different diesel engines, it produces way more power, not much more noise and a heap of whistle, never any engine related problems.

cheers mark.

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Good answer, to the point, thanks. I was toying with the same idea for a while now to put a straight through exhaust on my D22.

Kallie

Cheers Mud & Matt for ur answers, best of both worlds would be great..