Is 3 inch exhaust on aftermarket turbo GU too noisy?

Submitted: Wednesday, May 07, 2008 at 22:18
ThreadID: 57369 Views:2904 Replies:8 FollowUps:2
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Hi All,

Getting a DTS turbo fitted on my 99 4.2 N/A GU patrol wagon. I was keen on getting the 3inch exhaust fitted as the turbo comes with a 3 inch dump pipe. I may also install LPG in the future. More for economy than power.

The WA based installer of the turbo recommends 2.5 inch exhaust and says 3 inch will be too loud and will "trumpet". I spoke to a QLD installer who says go the 3inch the better they breathe in and out the better off you will be.

The GU is a daily driver/tourer so I don't want to go mad from exhaust noise.

1. Has anyone got the DTS kit with 3inch exhaust on ana N/A GU? How loud is it?

2.Can the LPG tank still be installed under the front passenger floor with 3inch exhaust? If not what exhaust mods are required as I would get these done at tubo fitment rather than cost myself more if/when LPG is fitted.

Any comments are welcome

Cheers
Mark


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Reply By: Member - Duncs - Thursday, May 08, 2008 at 07:49

Thursday, May 08, 2008 at 07:49
Noise levels are very much opinion based rather than a hard and fast data based judgement. Especially from the guy at the workshop when he is trying to sell you the exhaust system he likes.

If the 3" system give the best performance go for it, as long as it is legal you have nothing to worry about.

If it is a bit noisy buy some mud tyres, and crank up the stereo.

Duncs
AnswerID: 302617

Reply By: Robin Miller - Thursday, May 08, 2008 at 07:57

Thursday, May 08, 2008 at 07:57
I think both of those exhaust statements are correct Mark.

(3 inch gives a little more and is also noisier)

I have friends with both 2.5 and 3 inch and I think the noise is to much from the 3 inch system.

To be fair I don't like the drone noise from almost all modded exhausts, and consider it a significant problem.
I even put back the restrictors in my new trail bikes exhaust which dealers take out on delivery - they looked at me stranely when I insisted on being given the oem restrictors !

In a previous vehicle with exhaust mods I even fitted twin wall pipes , and extra muffler - not sure if this is still a viable option.

Robin Miller

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AnswerID: 302619

Reply By: Trevor R (QLD) - Thursday, May 08, 2008 at 08:52

Thursday, May 08, 2008 at 08:52
I got a 3" exhaust and find it fine for daily driving. Love the power from my GU, but as a bloke, would always love a bit more hehehe.

Go the 3".

Trevor.
AnswerID: 302628

Reply By: Member - Serg (VIC) - Thursday, May 08, 2008 at 10:24

Thursday, May 08, 2008 at 10:24
Mark,

I Do not have GU, but rather LC80 + DTS turbo + 3” exhaust. I would not say that it is very nosy – turbo kills a lot of noise and also it depends on what muffler do you use. I would say that under heavy acceleration 3” a bit nosier then 2” stock, but under easy driving there is no difference. Also I conclude that 2.5” is enough and jump from 2” to 2.5” is much more noticeable then from 2.5” to 3”. Also “straightening” pipe does much more then increasing diameter. From economy POV there is no difference, but bigger pipe get rid of exhaust gases faster, thus turbo spins happier on low revs and therefore deliver more punch quicker. With stock pipe I was able to get 10psi only on high load like going 100 km/hr uphill on 4-th or 5-th and with 3” one I can do it on 3-rd at 60km/hr.

Cheers
Serg
AnswerID: 302650

Reply By: Member - Matthew C - Thursday, May 08, 2008 at 12:14

Thursday, May 08, 2008 at 12:14
On an aftermarket turbo system,3" will make no real difference to power just slightly louder,we fit 2.5" systems to our DTS kits with good results.

The LPG tank is normally fitted under the rear passenger seat compartment and yes it can be fitted with a 3" exhaust BUT will need to be modified (at extra cost) if done at seperate time to turbo fit.

MAtt
AnswerID: 302669

Reply By: Member - MUZBRY (VIC) - Thursday, May 08, 2008 at 12:25

Thursday, May 08, 2008 at 12:25
Gday
Us young fellas work on the principal that " if its to loud , you are to old"
How about that Robin??
urray
Muzbry
Great place to be Mt Blue Rag 27/12/2012

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AnswerID: 302671

Follow Up By: Robin Miller - Thursday, May 08, 2008 at 16:39

Thursday, May 08, 2008 at 16:39
You must be one of those young fellas Muzbry - although the way you went across princess hwy opposite MacDonalds the other day made me think of other descriptions
Robin Miller

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Follow Up By: Member - MUZBRY (VIC) - Friday, May 09, 2008 at 07:59

Friday, May 09, 2008 at 07:59
Gday Robin
I would only drive fast if the police were chasing me...
Murray



Muzbry
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Reply By: bennspoon - Thursday, May 08, 2008 at 14:49

Thursday, May 08, 2008 at 14:49
depends alot on your turbo as well... I have seen GU 4.2 turbos with 3" from the turbo back that sound like stock until you give it heaps, but my 80 with a 3" is louder than a rice burner even after an extra muffler.
AnswerID: 302690

Reply By: rumpig - Friday, May 09, 2008 at 21:02

Friday, May 09, 2008 at 21:02
haven't got a nissan but a 105 series cruiser running a beaudesert exhaust 3" system and a DTS turbo and intercooler. i'm not a fan of noisey exhaust systems (must be getting old) and wouldn't consider my system loud. will say that by adding the intercooler it did make the turbo whistle alot louder and more noticable, but as for the exhaust it's not that loud. the cruiser does have pretty good sound proofing though, the ambulance that snuck up on me one day with sirens going is proof of that.
if your interested this exhaust company has a prety good name for themselves and posts australia wide.
AnswerID: 302961

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