exhaust 3 inch or 2 and a half

[vq_statss]

whats better for my car.its stock standed with a cai what do people recomend.im getting it from cat back for now.thanks

[redcv6]

i would go 2 1/2, but then again its your own personal prefrence in sound.
johnny

[VNexecutive]

im gunna belooking at the same question a little later on so here goes, whats the difference in sound? which one is louder? which one is deeper? etc

[padrickz88]

by what ive heard......
2 1/2 inch is fine for a v6, dont loose power and get sound
3inch? i heard its an over kill and you will loose to much power down low....

BUT im not 100% so ill wait till someone who does no 100% and yeah

[VNexecutive]

by what ive heard......
2 1/2 inch is fine for a v6, dont loose power and get sound
3inch? i heard its an over kill and you will loose to much power down low....

BUT im not 100% so ill wait till someone who does no 100% and yeah

cheers mate, i was thinking dual 2.5 inch dumpers. wouldnt loose too much power down low off that would ya?

[JSTPOZN]

2/5 is plenty for a v6 get some good extractors and your car should be sounding very nice

[padrickz88]

cheers mate, i was thinking dual 2.5 inch dumpers. wouldnt loose too much power down low off that would ya?

i wouldnt recomend you do what i say because im not 100%.... but by what ive read on this forum i think i remember if your going single = 2.5inch..... and if your going dual its better to get dual 2.25inch..... can someone who knows tell him? because im just going on by what ive seen around here

[VNexecutive]

i wouldnt recomend you do what i say because im not 100%.... but by what ive read on this forum i think i remember if your going single = 2.5inch..... and if your going dual its better to get dual 2.25inch..... can someone who knows tell him? because im just going on by what ive seen around here

lol its alright mate im not gunna go weld me some dodgy ones now, mod will be a few months away yet, but just athering ideas

[Not_An_Abba_Fan]

It comes down to how much you want to spend and your future mods. Stock motor: Extractors and 2 1/2" mandrel bent with a straight thru muffler on the front will give you the best top end performance and cruising economy. The sound will differ depending on whether you go for a resonator on the rear, personal preference there, no reso = drone. Do not get a hi flow cat unless you are going to s/c or turbo it because there will not be enough heat generated in an N/A engine to "light up" the cat, ie: let it do the job it was designed for. People will say that it gives more power with a hi flow cat, but this is not the case. On a dyno maybe but not on the road. Only when the original cat was blocked will a hi flow make a difference on the road. Also people will say I am full of crap but 22 years in the exhaust industry gives me an educated opinion. If you are going down the forced induction road then you can put on twin 2 1/4" with hi flows or even a 3" single. But at the end of the day it is your money and you tell the experienced exhaust fitter what you want even if he recommends something different. This may sound a bit sarcastic but sometimes I get a bit tired of the 'weekend warrior experts' who think they know more than the specialists. Please don't take this the wrong way....I'm only trying to give you what I believe is the best advice.

[pandaman]

whats better for my car.its stock standed with a cai what do people recomend.im getting it from cat back for now.thanks

I'm guessing yours is a V8? In either case stock standard a 2.5 inch is all you need power wise. A single 2.5 inch exhaust becomes a restriction at a power level of roughly 150rwkw, So stockers and mild mod 6's and 8's are pretty much fine with the 2.5 inch.

That said, if it's an 8 and you're planning a bit more work (or a V6 planning a LOT of work) the 3 inch gives you a lot more headroom to play with, sounds wicked as well. Just be prepared for it to feel a little doughy (comparatively) down low, but hey when it sounds that good who cares?

[vq_statss]

thanks people...ill take the advice given .its a 5lt.so use think 3 is to big wont be putting forced induction....maybe cam and stuff later...can some one explain what a resonator does.

[vq_statss]

and will i lose power down low with 3 inch.....somone please explain.ty

[vq_statss]

also will i need a tune with bigger exhaust or wait till i get new headers

[coolvxss]

The resonator Just changes the note of the exhaust. I ended up taking mine out and running a straight pipe because resonator made it too quiet for my liking.

[Not_An_Abba_Fan]

Shouldnt be too bad without a resonator on a 5lt. Its job is to take out certain frequencies in the exhaust. Different size resonators will do different things. Try it without 1st, if you dont like it, doesnt take much to weld one in.

As for losing power, petrol engines need back pressure to have low rev torque, if you go too big with the exhaust you lose back pressure and lose a bit of bottom end while increasing your top end. The best balance would be to use interference or 'tri y' extractors with a good free flowing 2 1/2".

[PaRaDoX]

yeah 3" on FI 2.5" on N/A

[pandaman]

thanks people...ill take the advice given .its a 5lt.so use think 3 is to big wont be putting forced induction....maybe cam and stuff later...can some one explain what a resonator does.

A 3 inch exhaust on a 5 litre isn't a bad thing really. There's a video floating around somewhere on here of a stock VP 5L with a 3 inch zorst flogging around a small hillclimb circuit, sounds amazing. But if you're staying fairly standard for the forseeable future then the 2.5 is probably the best option in terms of bang for your buck. The 3 inch might lose you a little bit of low end torque because it seriously reduces back pressure as the others have mentioned. Just depends on what you're after, nice and cheap power upgrade go the 2.5, or for the big noise and roughly the same effect on power go the 3 inch with the risk of losing a tiny bit down low.

Once I've got a decent tune and a few other bits and pieces on mine (within the next fortnight hopefully) I'm planning on getting a dyno run done to help decide what kind of exhaust and other bits and pieces are next in the plan.

[vq_statss]

yep 2 and a half it is......hi flow single muffler with oval tip(got me own tip)got a price $290 from cat back or $390 for 3 inch.sound about rite does it.thanks heaps

[burnz]

whats better for my car.its stock standed with a cai what do people recomend.im getting it from cat back for now.thanks

i have to assume your running a 5 litre
duel 2"-2.25" will do the job nicely

[38VNIT]

from my knoledge u loose rear end pressure power with a 3" on stock 6 motor, but then again u could put a 2.5 or 2.75" resegnator towards the end, is there any truth to this...

[vq_statss]

its a 5lt and i will be doing cam and alittle later...

[kniever]

just get a 2 1/2 thats what i got and it goes perfect

[younggun]

are u using your origanal cat??? i got a 3inch on my stato 5lt which is off the road at the moment have to remove it to get rwc and it sounds real dirty for the forst 3-4000 revs but after that sounds ****ing nice but yes lose a little down low not as quick off the line mate

[vq_statss]

yeh using original cat.

[greenfoam]

A 3 inch exhaust on a 5 litre isn't a bad thing really. There's a video floating around somewhere on here of a stock VP 5L with a 3 inch zorst flogging around a small hillclimb circuit, sounds amazing. But if you're staying fairly standard for the forseeable future then the 2.5 is probably the best option in terms of bang for your buck. The 3 inch might lose you a little bit of low end torque because it seriously reduces back pressure as the others have mentioned. Just depends on what you're after, nice and cheap power upgrade go the 2.5, or for the big noise and roughly the same effect on power go the 3 inch with the risk of losing a tiny bit down low.

Once I've got a decent tune and a few other bits and pieces on mine (within the next fortnight hopefully) I'm planning on getting a dyno run done to help decide what kind of exhaust and other bits and pieces are next in the plan.

That's TTVN's VP, it's exactly the same as my car except his is blue and has a 3 inch exhaust.

http://www.youtube.com/watch?v=XgdsWwt9nZs