2.5" or 3"?

[H.eng]

Im looking to put a new exhaust on my VE 6L automatic,just wondering if the 3" would give better performance than the 2.5?

[TinSnips]

no performance difference, assuming the motor is stock.

[RUF-60L]

just louder

[GKW]

Talk to your exhaust shop and tell them what your plans are re future engine mods and they'll recommend the right set-up. Unless you are planing some major internal mods to amp up the kw's, 2.5 should see you fine with the basic bolt on's (headers , OTRCAI) and tune etc.

[Lumps of cheese]

Heaps of threads on the issue, search and you will find.

[pjdm1980]

Got to make it a 3"!!! I've got 3" and it sound great.

[UFO]

just louder

hmmm..... louder isnt always better.
too big an exhaust and your car sounds like a wet fart and drones like all buggery. otherwise just go 5" from something like a kenworth and then it'll be really loud .

as already mentioned, have a good read through the VE section. brands and types discussed.
my thinking is this however... if you arent planning on doing any other mods, go 2.5". if you plan to tune and change air intakes and the like go 3", but hold off on the exhaust until you get the other bits done, THEN exhaust, THEN tune it all.

[RUF-60L]

pfft i didnt say louder was better, i have a 3" exhaust and i like the sound doesnt sound like a wet fart at all :/ dunno what v8s uve been listening too lol

[RUF-60L]

i did see a GTS with dual cannons on it not long after the VEs came out, sounded like a rexy (minus the pssssh) -_-

[UFO]

pfft i didnt say louder was better, i have a 3" exhaust and i like the sound doesnt sound like a wet fart at all :/ dunno what v8s uve been listening too lol

I know you didnt say loud was better, I was just adding to your comment... not disagreeing with it .
And I never said 3" sounds like a wet fart. I said "too big sounds like a wet fart", especially when poorly matched with the wrong muffler.

OP asked about performance gains... so I still reckon a 3" full exhaust is overkill if you arent doing any other work to the engine bay. I'd actually place a wager that you 'could' lose performance with a 3" and no other mods... but that's just my opinion.

[walesy]

twin 3in FTW! its not so much louder as it is a deeper note, basic reverberation principal its a bigger diameter so lower frequency

[WogBoyz]

just louder

I found my 3" kpm isnt that much louder really, just more deep then the 2.5s ive heard

[H.eng]

Thanks for the info fellas yeh its got the otr intake extractors,tune and the cats removed all before i bought it but for some reason it still has the stock exhaust.

[RUF-60L]

Cats removed??? o_O

[H.eng]

yeh there is a 2.5" pipe in there place which connects the extractors to the stock exhaust

[jr689]

Jeez mate, you could have atleast gutted the cats to make it not look so suss haha

[HUX 90]

No cats? I thought exhaust systems had better flow with cats? At least thats what APC told me.

[Munz]

twin 3in FTW! its not so much louder as it is a deeper note, basic reverberation principal its a bigger diameter so lower frequency

100% true

No cats? I thought exhaust systems had better flow with cats? At least thats what APC told me.

Haha APC clowned you (sorry couldn't help myself)

but yes it is illegal

[jr689]

No cats? I thought exhaust systems had better flow with cats? At least thats what APC told me.

I heard something along those lines but slightly different... That high flow/performance cats flow better than or equal too gutted/no cats ... Sooooo in other words it's not worth the risk of having no cats when you can get similar results from high performance ones...