High flow cats

[vxcp]

I have 2 twin high flow cats on my twin system atm and ever since i but them in its been a little less gruntier and more noiser attracting police all the time. I live in QLD and was wondering is it legal to take the cats off and just have a straight threw exhaust or put stocks back on??? And also i saw this cats on ebay (High flow Cat 2.5" 100CPI Stainless Commodore V8 V6 Ford | eBay) im not sure if mine are 100ci or not no nothing about cats. And looking at the ones on ebay thats cheap seeming i paid $375.00 a pop for mine =(. So what would my best option be:

1. Take both cats off
2. Put standards cats back on
3. Take on cat off
or
4. Buy the ones off ebay

Note: exhaust has a rear ressy on it...Thanks for help in advance

[Not_An_Abba_Fan]

The reason it is "less gruntier" is too much back pressure and not enough exhaust velocity. I'm guessing the system is twin 2 1/2"?

You could try fitting an X pipe behind the cats, this will speed up the exhaust flow and give you some bottom end back as well as make it a bit quieter.

[wraith]

Never mind got NAAF'd

[Tommo_27]

If you run with no cats and get caught its something like a $10000 fine I believe.

[vxcp]

The reason it is "less gruntier" is too much back pressure and not enough exhaust velocity. I'm guessing the system is twin 2 1/2"?

You could try fitting an X pipe behind the cats, this will speed up the exhaust flow and give you some bottom end back as well as make it a bit quieter.

So i should ask my exhuast shop to fit an x pipe behind the cats??, anything else ud suggest and also how much we looking at roughly for that to happen also just a rough estimante. thanks

Also fitting the pipe will it change exhaust sound or keep the same??

[vxcp]

If you run with no cats and get caught its something like a $10000 fine I believe.

Damn well scrap that haha thanks for the heads up =)

[bigjim92]

So i should ask my exhuast shop to fit an x pipe behind the cats??, anything else ud suggest and also how much we looking at roughly for that to happen also just a rough estimante. thanks

Also fitting the pipe will it change exhaust sound or keep the same??

From what I read Pacemaker have an X/merge pipe which is meant to be pretty good, and it will change the exhaust sound.
Pacemaker Headers Australia - Quality Performance Exhaust Headers :: Exhaust System Catalogue

[Not_An_Abba_Fan]

So i should ask my exhuast shop to fit an x pipe behind the cats??, anything else ud suggest and also how much we looking at roughly for that to happen also just a rough estimante. thanks

Also fitting the pipe will it change exhaust sound or keep the same??

Yes, just behind the flanges where the twin system comes together. An X pipe is about $100, and roughly $50 or so to fit it. Apart from changing the whole system, that's about it.

The note will get smoother and quieter.

[vxcp]

nice guys thanks for ur help im going to do what NAAF after all he is the exhaust guru =) (oh just so i dont sound like an idiot talking to the exhaust fellas do i say i want an X pipe just behind the cats or wat exactly do i say so they no what im talking about and no one gets confused??)

Cheers Fellas, getting my spacers, insulator and CAI very soon as well cant wait

[Tommo_27]

Sorry to hi-jack thread

Yes, just behind the flanges where the twin system comes together. An X pipe is about $100, and roughly $50 or so to fit it. Apart from changing the whole system, that's about it.

The note will get smoother and quieter.

I have a ve sv6 with standard exhaust plus pacmaker extractor and redback rear mufflers and it drones at some points. If I were to fit an x-pipe will that make it quiter/drone less? Where should i fit it?

Ive heard people say to cut out the hotdogs/crimp section after center muffler and put xpipe in place of that. Any good you think?

[vxcp]

na all good man topic is about hi flow cats =p guess ull have to wait for NAAF to reply mate

[Not_An_Abba_Fan]

This is the X pipe you want to fit



And you need it fitted here



Here is one I prepared earlier, this one I fitted to our Senator. Perfect spot on a V6 but too far forward for a V8.

[Not_An_Abba_Fan]

Sorry to hi-jack thread



I have a ve sv6 with standard exhaust plus pacmaker extractor and redback rear mufflers and it drones at some points. If I were to fit an x-pipe will that make it quiter/drone less? Where should i fit it?

Ive heard people say to cut out the hotdogs/crimp section after center muffler and put xpipe in place of that. Any good you think?

Yep, there will be fine. Yes it will reduce drone, but the main problem is the Redback mufflers. Fitting larger diameter pipework after the standard size will create a trumpet effect and cause the drone. Change the front section to the larger size as well and it will reduce the drone as well. But the downside to that will be losing a bit of bottom end. The X pipe is probably the best solution.

[Tommo_27]

Thanks for the info mate. Sent you a pm.

[vxcp]

still abit confused are those the cats at the back that the X pipe connects to (in the third picture)??

sorry for all the stupid questions i dont want an exhaust shop putting it somewhere completly different and making to improvement wat so ever because i didnt undertand what ur saying.

So i have my extractors right. Does the X pipe come off the extractors and bolt on to the cats is that what ur talking about or am i off by a long shot.

Cheers

P.s by the way thanks for putting the time into showing pictures and even taking a photo off one of them man.

[Munz]

NAAF Why is having an Xpipe after the cats before the centre mufflers to far forward for a V8? And where would you put it?

[Jarp]

I reckon the Xpipe in a V6 is the best thing to do. I've got mine placed after the mid-muffler where the crimped section was. I think it helps to keep the rear cans fuller therefore reducing (not stopping) very low rev reverberation. Also mixes the sound up a little more. An xpipe in a stock system in effect also creates a system with two crossovers as I think the mid-muffler also has a h-pipe/perforations arrangement within.

[Not_An_Abba_Fan]

In the thrid picture you are looking towards the front of the car. The wheel you see is the front wheel. You can see the extractors coming down off the engine, then the cats, then the flanges where the system bolts up, then the X pipe. It is fitted in the exact place I have pointed to in the second picture.

Munz, after fitting the X pipe there on our Senator I noticed an increase in acceleration but a slight loss in top end. I put it down to how the X pipe actually works and how it was slowing down the exhaust flow at high revs.

The X pipe works by crossing the exhaust pulse from one bank to the other speeding up the exhaust flow by adding an extra pulse to that bank. On a V8 you have 4 pulses per side, the X pipe makes it 8. Fitting it closer to the engine speeds up the exhaust flow at lower revs aiding the scavenging effect and reducing back pressure, as the revs increase the pulse get too close together as they are moving faster and as a pulse crosses over, my theory is that it clips the back of the preceding pulse on that side actually slowing it down.

To fix this, I removed the two front mufflers and fitted the X pipe there, this had very little effect on the bottom end but increased acceleration right through to the rev limiter. On a V6 the pulses are further apart so putting the X pipe closer to the engine works better on them.

[vxcp]

ok so extractors then cats then Xpipe then muffler, ill be ringing them today and finding out a quote and what not thanks

EDIT: Public Holiday lol no go

[Not_An_Abba_Fan]

Yes, fit the X pipe right behind the flanges off the cats where the two sides come together.

[vxcp]

just rang the dude that done it he said he would of put an x pipe on it he wouldnt of not put one on becuase its a stupid thing to do not putting one in and washed my car yesterday cleaned out the exhuast and now it sounds the way it did when i first got it so dont need to do anything to it. But to make sure i have the X pipe he said bring it in and we will put it up and have a look so ill do that just in case

[Not_An_Abba_Fan]

How did you "clean out" the exhaust?

[vxcp]

with a scubber on a stick u no what im talking about and use water alot of black shit in there i must say

[ryan101]

Exhausts sound better with all the black soot

[Not_An_Abba_Fan]

^^ I agree. Mellows the note out more.

How can cleaning the tail pipe make it quieter? Weren't you saying it was too loud?