[Divv]

Hey guys,

I have  Turbo Diesel i30 2012 GD, and I am looking at removing the muffler and welding a straight pipe onto it.

My question for today is whether or not it is legal in Australia first of all, as well as is there any issues with sensors and ECU's etc?

Look forward to your response,

Divv

[TerryT]

Divv, removing a muffler from a road car will increase the vehicle's exhaust noise to a level above EPA requirements...so, illegal.

NSW EPA site: Avoid having noisy vehicle exhaust.

SA EPA may be different but I doubt whether enough to accept unmuffled road vehicles.  [Edit: SA.GOV.AU - Engine and exhaust modifications].

It comes down to NOISE although emissions (carbon dioxide %) will count with the EPA.  And, removing the muffler may affect "sniffer" sensors but I don't know enough about that aspect.

Not a mechanic, just my 2 cents worth while one of our more technically-minded members answer.

[CraigB]

If you're wanting a more sporty sound I'd be inclined to replace the heavy standard rear muffler with a straight through sports type like a Walker Turbo, that will stop the exhaust being to loud.

Sensors would only detect an emissions change if removing the Catalytic converter.

[josh1990]

What are you hoping to achieve with the straight pipe?

It won't sound much better (if any), it's a small capacity diesel and the turbo itself has a muffling effect. You may build boost a fraction sooner - not enough to notice other than placebo. Most vehicles have 2 mufflers (don't touch the catalytic converter - a) horrendous fine, b) sensors) so you'd ideally take the larger muffler out. This can introduce resonance at cruise speeds that will drive you insane. It might not either. I've had my xr6 passed for rego in NSW with its rear muffler removed for 3 years before I did the full exhaust. I honestly could barely notice the difference between that and a stock xr6 until I did the sports mufflers. Walker turbo is a great recommendation - flows great, sounds great (I've had on my old XF, went from stock to hotdog to walker turbo so had comparisons) and more importantly looks the part should any one want to inspect. It all comes back to my original question and what are you looking to get out of it?

[Divv]

Divv, removing a muffler from a road car will increase the vehicle's exhaust noise to a level above EPA requirements...so, illegal.

NSW EPA site: Avoid having noisy vehicle exhaust.

SA EPA may be different but I doubt whether enough to accept unmuffled road vehicles.  [Edit: SA.GOV.AU - Engine and exhaust modifications].

It comes down to NOISE although emissions (carbon dioxide %) will count with the EPA.  And, removing the muffler may affect "sniffer" sensors but I don't know enough about that aspect.

Not a mechanic, just my 2 cents worth while one of our more technically-minded members answer.

Hi,

Thanks for your response.

I removed the muffler at the very back and welded con a straight pipe with two bolts and it sounds fine so far. Not drony at any rev range and does sound a bit nice.

The laws only refer to stationary noise levels - such as at idle - on or after 1 January 1983, the stationary noise level when tested must not exceed 90 dB(A).

And my car sounds the absolute same at idle, its only, when you put your foot down, does it make a bit of noise. And even then, its not overly loud which is good. Took it for a quick drive last night and when putting into a cruising gear it sounds absolutely normal. - no dronyness etc.

Thanks,

Divv

[Divv]

If you're wanting a more sporty sound I'd be inclined to replace the heavy standard rear muffler with a straight through sports type like a Walker Turbo, that will stop the exhaust being to loud.

Sensors would only detect and emissions change if removing the Catalytic converter.

Haven't touched the catayctic converter. Only removed rear muffler and welded together a straight pipe which then bolted on to the exhaust.

I did read the importance of having the exhaust pointing down away from the car and not up or straight back as it can melt the muffler.

Thanks,

Divv

[Divv]

What are you hoping to achieve with the straight pipe?

It won't sound much better (if any), it's a small capacity diesel and the turbo itself has a muffling effect. You may build boost a fraction sooner - not enough to notice other than placebo. Most vehicles have 2 mufflers (don't touch the catalytic converter - a) horrendous fine, b) sensors) so you'd ideally take the larger muffler out. This can introduce resonance at cruise speeds that will drive you insane. It might not either. I've had my xr6 passed for rego in NSW with its rear muffler removed for 3 years before I did the full exhaust. I honestly could barely notice the difference between that and a stock xr6 until I did the sports mufflers. Walker turbo is a great recommendation - flows great, sounds great (I've had on my old XF, went from stock to hotdog to walker turbo so had comparisons) and more importantly looks the part should any one want to inspect. It all comes back to my original question and what are you looking to get out of it?

Well, after setting it up, and doing the work, it sounds pretty good so far. Not obnoxiously loud, and only makes a nice growl when you put your foot down. I tested it in all gears at a range of speed, and when cruising I noticed it sounded just like normal, only when you put the foot down does it make some noise.

Def's aint gonna touch the CAT, and only removed the rear muffler.

Im not sure if its too big but I made the exhaust a 3" as it was an old tractor one.

Do you think thats too big?

Divv

[TerryT]

Divv, removing a muffler from a road car will increase the vehicle's exhaust noise to a level above EPA requirements...so, illegal.

Hi,
Thanks for your response.

I removed the muffler at the very back and welded con a straight pipe with two bolts and it sounds fine so far. Not drony at any rev range and does sound a bit nice.

The laws only refer to stationary noise levels - such as at idle - on or after 1 January 1983, the stationary noise level when tested must not exceed 90 dB(A).

And my car sounds the absolute same at idle, its only, when you put your foot down, does it make a bit of noise. And even then, its not overly loud which is good. Took it for a quick drive last night and when putting into a cruising gear it sounds absolutely normal. - no dronyness etc.

Thanks,

Divv

Thanks Divv.  I had always thought that removing a muffler would always put a car above the EPA noise levels...but apparently not always.  So, something else I have learned this morning (first was when eating breakfast cereal, always align your mouth with the spoon ).

[TerryT]

Sensors would only detect an emissions change if removing the Catalytic converter.

CraigB, thanks for that clarification.   

[CraigB]

Sensors would only detect an emissions change if removing the Catalytic converter.

CraigB, thanks for that clarification.

You're welcome