Cat or Decat

2nd June 2004, 00:02

I've heard alot of different types of exhaust - Decat catback cat. what do i need for better performance?

2nd June 2004, 00:51

get a btb exhaust they decat the car. there are ment to be the best for performance on saxos??

2nd June 2004, 00:52

where can i get one?

2nd June 2004, 17:04

expensive though. www.gmcmotorsport.com and if you want to know about exhausts read the section there to

29th June 2004, 21:05

I've had a BTB on VTR for about 7 months now with the heatshields removed. Fitted by GMC all in for £385.00 and it looks just like a standard 'zorst at the back but sounds great.They have what LOOKS LIKE a cat on the middle section (it ain't). Only thing to remember is you need to get your garage to HELP you with your emissions; if you know what I mean.
Exhaust is MINT - got progrssively louder for the past 6 months but has settled now. I would recommend to anybody - nice dull rumble when idling; and noise when you want noticed.

30th June 2004, 13:14

is a BTB a full system right through car or just the manifold/downpipe part??

I've got standard manifold/downpipe on mine and the a straight through pipe from powerflow. Would changing the manifold make any difference do you know?

Are powerflow exhaust any good for performance or are they just purely for noise and style??

30th June 2004, 17:08

i would say purely for noise and style really unless you asked for specific bore and placements of boxes etc...

a manifold will make a BIG difference, the standard manifold is very restrictive.

You can also buy manifolds from GMC

30th June 2004, 18:57

could you modify the original manafold?

30th June 2004, 19:56

So, if you remove standard manifold and replace with a 4 branch, this removes cat, yeah. Then basically, a straight through pipe will run right through the car.

Would that be really rasspy you think???
And will it increase power?

I spoke to powerflow other day and asked them if they thought the exhaust may be causing me to loose power and they said they had never heard of anything like this before? anybody think they are lying?

30th June 2004, 20:35

well they are not going to say that it will loose power are they

If your car has the cat in the manifold tehn an after market manifold will remove the cat but if its under the car you will need a decat pipe to remove it

1st July 2004, 04:41

would changing the manifold on a vts use up more petrol? i had a decat janspeed on my 106gti, amazing noise but the petrol it used up was crazy, ive a foot of lead though

1st July 2004, 05:12

its the heavy foot

1st July 2004, 06:41

most likely, its too tempting theres a deadly loud rasp after 4000rpm!!!

Does a 4-1 branch use up more petrol, even with my foot?

1st July 2004, 06:49

it itself will not use up more fuel as it is just allowing the exhaust gases to escape but it may use more fuel as teh cyclinders are cleared of the gases quicker leaving more room for fuel to be pumped in, again its goign to be hardly noticeable but its the heavy foot that does the damage

3rd July 2004, 17:02

get rid of the cat. piece of shit thing. got rid of it the other week. feels alot smoother to drive. supersprint 4-2-1 manifold and system made a heck of a difference

4th July 2004, 05:09

Quote:

Originally Posted by powerhungry

get rid of the cat. piece of shit thing. got rid of it the other week. feels alot smoother to drive. supersprint 4-2-1 manifold and system made a heck of a difference

Is yours a VTS? What do you reackon you get mpg?

10th July 2004, 15:16

its a vtr mate. get roughly 270 miles per tank, but its had fair bit of mods under the hood. check out spec list in users cars mate

11th July 2004, 04:00

Did you get the manifold when you got the system?

13th July 2004, 15:49

yeah got the whole thing at once. lambda sensor goes into the manifold

14th July 2004, 19:02

I just got a new Green forced air induction kit for my 1.4, and it sounds and feels sweet!!! I want to get an exhaust system as a next step. What are the parts to be changed, and what does it mean to cat or de-cat the saxo?

Can I get a brief introduction on exhaust systems and what I need to change?

14th July 2004, 20:07

the exhaust will already have a cat (catalytic convertor). Depending on the year of the car either mk1 or mk2 the cat will be in different places, on mk1 it is under the car almost directly under the handbrake, on a mk2 it is within the manifold.

Different types of exhausts;
Backbox: this is just the end box that you can see sticking out the back of the car.
Cat Back system: This is a system from the cat backwards, it does not replace the cat. Even if its a mk1 or mk2 the cat back system will go from the place the cat would be on a mk1 backwards. This system comprises of the centre section and back box.
Decat pipe: On a mk1 this pipe replaces the cat
Manifold: The biggest power gains will come from this when combined with a full system. This is the bit that attaches to the engine then sweeps underneath the engine to meet the centre section/cat.

Ideally you want to start with a cat back system then go for decat (or if you want to keep things in perfect tuning a small box to replace the cat) and then a manifold.

16th July 2004, 16:03

Thanks a lot for the info scott. I think I got it how it works. I will start with a cat back system.

I have an mk2 saxo, but I dont know whether I should go for decat, because I dont know about the advantages and dissadvantages really. But when i will replace the manifold, will the cat be replaced compulsory?

I want to get the whole back system, and also change the manifold. But I dont know what to do with the cat.

Any suggestions for the whole operation? (brands as well?)

18th July 2004, 04:29

Im getting about 300miles to a tank on the vts so im happy. dont want to start decreasing it anyway.