[FullyZooked]

Hey guys getting a new exhaust tomorrow and just interested in peoples opinions, experience with what size?

I am having the lot replaced- cat and muffler as well as all plumbing in hope that my original cat has collapsed and causing the poor running.

I was thinking a 2 1/4 setup for good flow and to give the old girl a bit of a note

Opinions? What are you guys running on the vits and sierra's?

[Westie]

You do 2 1/2 all the way and you will have a dog of a car down low..
After the cat 2 1/2 OK but out of the extractors get them to make up a Inner pipe reduced down to 1 3/4 " and slip that into the front pipe before the Cat this will help with low down toque. I had this mod done to mine and it makes a differance. What they do is drill a couple of holes in the main pipe 1/8th then slip the reducer in and tack weld it in place through the holes.

Reason ....is if you get to much free flow out of the extractors it holds the heat/gas into the exaust instead of pushing it through the system.
With the reducer in place it causes preasure and pushes it through the system.

I know some may not agree but this is and old trick and some OLD school guys will know about it. I know it works and works well.

Noise always make the car feel like it has more power and in the high revs, yes this can be the case but most of us wheelers want tourque down low. You still will have noise with the above mod and you will increase down low tourque as well.

[buzbox]

I think my vit has 2" from the extractors back and it's a good note, It's loud but not shitty droney sounding loud if you know what I mean. The previous owner had it done so I can't really comment on before and after differences.

[atari4x4]

i think i'm running a 2.5" press bent from the stock headers back with a hi flow metallic cat & muffler & i can't say i've noticed any lack of low down torque, but i do have more torques than the average vitara.

EDIT: it's 2.25" according to my build up thread

[EldarO]

1.5" pre cat, 2" post.

goes alright.

[FullyZooked]

Sorry typo guys. Meant 2 1/4. Thanks for the input btw.

[TheRealCJ]

I got a 2.0 inch exhaust from the Cat back, after I cracked the Hotdog during some particularly rough rockwork (I have a 96' Tara).

I've got a pretty nice note, and the power increased noticeably.

[Fatzook]

2" for 1.6L
2.25" for 2.0L

[DarkHorse]

+1 for 2" in 1.6 - sounds and feels great.

Extractors are probably 1.75, stock cat, 2 from there back.

[MacDaddy]

X 3
I really wouldnt go any bigger than 2in for a 1.6, or you will have reduced power in low RPM... i had a 2in put on my 1.6 Vit, when i had it...

I have a 2in sports exhaust, with High Flow Cat, and straight thru muffler on my GV, and it made a heap of difference, once i hit 3000rpm, you can feel it really take off, and it gives my GV a really nice exhaust growl now... sounds a bit like a rally car, he he...

[FullyZooked]

2 inch it is! Thanks fellas!

[stocker]

Yewww for 2" mine sounds great. and now yours shall too

[FullyZooked]

Just got a call from the exhaust mob.

The cat converter was so heavily broken and collapsed that he didn't even think it could run.

I have gone all out now I know that this is where the problem lies.

We have gone for some shiny new extractors, 2 1/4" hi-flow cat, 2" plumbing through to the sports muffler and hopefully still come out the back not sounding like a ricey on crack.

You would not believe how excited I am to get her back on Thursday! I'll be heading straight to the highway and showing the 100km/h sign who's boss!!

I will let you know how she goes. Oh BTW, when is our next Vic trip?! I will be able to travel over 150k's to a tank YAY!

[atari4x4]

i will be a different car to drive, i dare you to take it back to the mechanic that did the carby rebuilds...

[ollies]

Top stuff! Hope all is well with the vit now

[Westie]

Should have just punched the cat out and got all the crap out like most of us did and stick with the setup we said. Hope it all goes well for you.

[MacDaddy]

FullyZooked wrote:

Just got a call from the exhaust mob.

The cat converter was so heavily broken and collapsed that he didn't even think it could run.

I have gone all out now I know that this is where the problem lies.

We have gone for some shiny new extractors, 2 1/4" hi-flow cat, 2" plumbing through to the sports muffler and hopefully still come out the back not sounding like a ricey on crack.

You would not believe how excited I am to get her back on Thursday! I'll be heading straight to the highway and showing the 100km/h sign who's boss!!

I will let you know how she goes.

Yep... the cats are only designed to last a few years, 5 years tops, then they just degrade and block up....
Cool ! Sounds like you got a good system put on now... you may notice it straight away, or it may take a little while, but you will notice an improvement in engine performance, i have always had a very good improvement... it may or may not give you more top speed, but it will get you to its top speed quicker than normal... after a few weeks you begin to find that " sweet spot " in the rpm range... next time we hear from you, you will have a big smile on your face !

[Microwire]

Good to hear your new zorst is on the way. I'd be interested to know the power difference.

On a slightly different note, I've got extractors (not sure on the diameter) would punching out the cat and welding it back in make a differnce?

[Westie]

he cat is stuffed and rattleing then you should be able to get a lwnght of pipe andpus it through and s,ash up what is left in there and then when you start it up aging there will be heaps of shit flying out the back.

[MacDaddy]

Westie wrote:

he cat is stuffed and rattleing then you should be able to get a lwnght of pipe andpus it through and s,ash up what is left in there and then when you start it up aging there will be heaps of shit flying out the back.

I am just picturing all that shit flying out the exhaust...

That would only work if you have a straight thru exhaust, otherwise you will block up the muffler...

[royce]

Microwire wrote:

Good to hear your new zorst is on the way. I'd be interested to know the power difference.

On a slightly different note, I've got extractors (not sure on the diameter) would punching out the cat and welding it back in make a differnce?

If its stuffed it might, if its not its unlikley youll notice

It must also be said that there are very specific and harsh penaltys for playing with the cat, as without it the stuff coming out your tailpipe is a lot worse than anything coming out of any car in the 50's or 60's

[Microwire]

maybe I should rethink my idea then, it's basically a cheap grab at the chance of some extra power. Does it being a weekend car only make any difference in justifying it ?

[royce]

no need to justify with anyone, jsut adding info so you cant later say but I didnt know

[DarkHorse]

Microwire wrote:

maybe I should rethink my idea then, it's basically a cheap grab at the chance of some extra power. Does it being a weekend car only make any difference in justifying it ?

Might help you justify it, but EPA/police/courts won't give a f*ck.

[Microwire]

hehe yeah you're probably right, I thought I'd take it off and have a look if it's ok anyway. Turns out there's nothing in it just empty space. Not sure what they look like normaly but I don't think this was it.

[atari4x4]

sounds like someone's already fixed it... usually there is a honeycomb type matrix in a cat.

[Marked]

I used to work in the exhaust industry...
the cat does not restrict your flow much.
There are thousands of crevices inside there and if you are really worried, you can buy a high flow cat...but not if your budget is stuffed,

One of the most neglected areas is the cat sensor. the amount of blokes who replaced that and found better economy and performance was amazing.

A cat should actually last a decade at least. the reason they stuff up is because oil gets into them from the motor, that causes them to overheat, and then caput as the ceramic insert degrades and goes brittle. I used to analyse them if they were able to be covered under warranty, and rarely a failure was the cat fault.

The above advice about 2.25 inch on a 1.6 motor is sort of correct.
The maximum I used to advise was two inch. You do need a certain amount of back pressure for the standard motor to work well. But 2 and a quarter is not over the top.

Check the size out of any hot dogs they put on. Often they will put a standard 2 inch ever on a 2.25 system, because they dont make many 2.25 inch hot dogs, they are rare.

And imho extractors will always give you more performance and economy over a sports exhaust, not many cars come out with good headers.

[Microwire]

heh yeah there was none of that in there. Shame in a way I would have liked to do that myself so I can feel a difference. Maybe I should just turbo it, that's a good exhaust mod.

[Marked]

if there is nothing inside, someone has punched out the guts. It might actually be detrimental to the car as all the sensors will be out of whack. It might actually decrease your performance.

[Westie]

The thing is what are the chances of getting pulled over and have an emission test done if you are not blowing heaps of smoke Etc anyway.
Leave the cat hollow and the outside loks in good condition then even if you went for a RWC they would not know any differant.

Just don't let the exaust guyknow cause they may say no we won't do your exaust if so drive around the corner to the next guy.