Twin 3" v's twin 2.5" exhaust

[VILLAIN]

I'm after peoples thoughts on which is better for performance.
I have heard that the twin 3" is worth 5-10 rwkw but on the track is it robing the car of speed due to the extra weight.

[planetdavo]

http://www.ls1.com.au/forum/showthread.php?t=73048&highlight=twin+inch

[Ridin-High]

Twin 3" would be to big on a stock clubby? unless it was blown

[vyssbeast]

Generally people stick with the 2.5" untill they get into serious hardware. But some upgrade to dual 3" with just a cam upgrade, gives abit more through the range and sounds awesome. Not necessary but its your call.

So basically if you plan on going into serious hardware at some point, cam, heads, blower, turbo, get the dual 3"... if your sticking bolt on strictly, or at most a cam (but unsure) probably stickwiththe 2.5" to be safe

[Azimuth]

Going from 2.5 twins to 3 twins is a 50% jump in volume per bank.
2.5^2 versus 3^2 is 6.25 against 9. You'd need some serious gas volume from your block to be worth the size increase. I'd say lower end torque would drop too. Others here may know how it would effect it.

[RED R8]

Generally people stick with the 2.5" untill they get into serious hardware. But some upgrade to dual 3" with just a cam upgrade, gives abit more through the range and sounds awesome. Not necessary but its your call.

So basically if you plan on going into serious hardware at some point, cam, heads, blower, turbo, get the dual 3"... if your sticking bolt on strictly, or at most a cam (but unsure) probably stickwiththe 2.5" to be safe

What he said ^^^^ I went twin 3" because the twin 2.5" didn't have the exact sound I was after so it was mostly bought for the sound factor..I have a cam only and performance wise there was no drop in mid range power but top end revs easier with the twin 3" so like said above stick to that basic principal and you cant go wrong.

[VooDoo]

I put a twin 3" on the cam only barge (216/220@114) and got PB's (with an extra 30-40kg). No loss of power or torque. I just put a twin 3" on the GTO which is unopened and gained another 8kw (222rwkw stock, 246rwkw tuned but 100% mechanically stock and then 254rwkw with the twin 3")

The best thing is the sound of a twin 3" is awesome. MUCH better than a twin 2.5"

[morey92]

The best thing is the sound of a twin 3" is awesome. MUCH better than a twin 2.5"

Agree 100%. A neighbour has a Monaro, think he has a twin 2.5", sounds good at idle and low revs. l have a twin 3" and the sound blows the 2.5" away. At idle, sounds fantastic, but anything above that, it sounds insane. Car runs heaps better. ( but had a lot of work done at the same time ) l would hate to think how it would sound with a bigger cam in it. Go with the twin 3", you'll love it :yahoo:

[BLACKWAGON]

Go and have a listen to a few of each and different brands, its gonna come down to what u like in the sound depo.
I love the sound of mine cammed with 2.5, not too loud but heads always turn.
alot of people want real loud and alot dont.
I dont like volume if it doesnt have a quality sound, but with either of these sizes u have a few brands and setups to choose from which will bring a big smile to ur dial.

[dogsballs]

No loss of power or torque. I just put a twin 3" on the GTO which is unopened and gained another 8kw (222rwkw stock, 246rwkw tuned but 100% mechanically stock and then 254rwkw with the twin 3")

The best thing is the sound of a twin 3" is awesome. MUCH better than a twin 2.5"

same here, totally bolt-on, didn't loose any power or torque over twin 2.5 sureflo. sounded 100x better and most importantly ran faster straight away (eventually getting a 11.95). this was pacie 4-1, twin 3 inch metal cats, twin 3 in x-force.

[VILLAIN]

Thanks for your input guys, is there anyone who has compaired the two on the drag strip.
It's not a sound thing or getting more hp but if the extra weight counter the extra power gain therefore not making any gains on the race track.

[markone2]

Twin 3" over 2.5" twin is worth 1/10th at the pointy end of 11 seconds.....cam only ...thats all...:)


the 2.5 twin system being highly underated imho....

[pauls350]

Hi Guys, Had pacy's and 3" twin stainless with hi flow cats put on my gen3 vx ss, at the same a vy ss had 2.5" put on thiers, I had a 30 hp gain over the vy, not sure of what else they had done, but quite a difference, mine sounds awesome at idle it just rumbles and gets a lot of looks at the lights, give it a gut full and the sound just blows ur mind

Paul

[11SLI]

with the GenTT setup on my ute and already having a twin 2.5in setup on it, i know the twin 3in is the ideal setup to get the airflow happening and make things easier on the motor but will it actually louden up the car alot taking into account the turbos and std headers already muffle the sound??

And it will obviously increase the power output, but will it make the motor a touch more safer in being able to flow easier etc?

[macca_779]

Great thread guys. I was always under the impression that on a bolt on car 2/2.5 would be the best option. The experiences discussed here have proven otherwise. I know which way I will be going now.

[vyssbeast]

Dont think it'll be much louder mate, i had a GenTT do a flyby on the freeway with a twin3" ... wasnt crazy or anything ... Since your a validated member check out the videos from chevs and listen to the Black VY take off.

Dont know about your other question though. Might be abit less backpressure on the motor... not sure

[11SLI]

Dont think it'll be much louder mate, i had a GenTT do a flyby on the freeway with a twin3" ... wasnt crazy or anything ... Since your a validated member check out the videos from chevs and listen to the Black VY take off.

Dont know about your other question though. Might be abit less backpressure on the motor... not sure

No problems, thanks for the speedy response :) might have to look into the videos as i havent looked in that section before

[ello]

Twin 3" would be to big on a stock clubby? unless it was blown

I was told the same thing with my VE SS L98 motor. After doing more research and speaking to more people who had the numbers on paper, I elected to purchase a 3inch Surflow system - Best thing I did. The extra power it gave me was more than what I expected, the power is constant right through the rev range - not to mention sound :rofl:

Saying this I had a VXII Cluby, put a 2.5inch Remus system on it, nice sound and well developed system, but now I look back definatley not in the same league.

[GMMAD]

i am getting a twin 3" on monday i have a sureflo 3.5 atm will be good to see difference it makes in sound and performance

[dogsballs]

to summarise. they are not too big for a stocker and the car will run quicker (and will not loose power or torque). saying that as markone2 has mentioned the gains over a twin 2.5" are very small, but for people chasing every last 10tenth it is worthwhile.

[EXCESSV]

the better sound and better power with the option of it accomadating mods later on are the reasons i have chosen dual 3" for my VE SSV...more on the sound than anything tho.

now just a waiting game till i drop it off in a couple of weeks.

[mustanger]

My GTS is booked in for a 3" Xforce stainless on Thursday . We will see how it goes.......:)

[Uncle Tone]

My GTS is booked in for a 3" Xforce stainless on Thursday . We will see how it goes.......:)

Where are you getting it done mate?

[mustanger]

Tidd Bros Spotswood :)

[vpstroker]

i got a twin 3 inch on our vzclubby R8 the sound is awsome dont care about the power factor just the sound .
so id go for the twin 3 inch mate for sound and future upgrades on motor