2.5V6 cats vs 3.2GTA cats

Can anyone tell me the difference in the cats from a 2.5 and 3.2?

I recently ordered new gaskets for my GTA and they are the same as the 2.5 so maybe the pipe diameters are the same.

Reason I ask is I could get a 2.5V6 set of cats and get the actual cats cut out and two straight thru pipes installed instead. Reason for the 2.5 cats is availability and cost. GTA cats second hand even are a fortune Im sure.

Just a thought.
-pablo

pipe diamter is not the same.

cool that sorts that! thanks.

Not quite.

Most 2.5's are euro 2 spec. Tubular manifolds and a single cat. SOME 2.5's were made as euro 3's.

GTA's were all euro 3 spec. They have cats in the manifolds and 2 further cats down stream in the mid section, making 4 cat's in total.

The 2.5 and GTA manifolds appear to be identical - part numbers match. However the 2 cats in the mid section are different part numbers. Why? Probably as has been said before - bigger pipe diameter.

I have a front manifold off a GTA for sale....

what do you mean manifold? the front pipes?

Additional: The mid sections for GTA's and 2.5's are the same price. ~£750.

Originally Posted by pablo

what do you mean manifold? the front pipes?

The front pipes are the same for Euro 3 2.5 and GTA. Euro 2 2.5 front pipes are very different and will not fit.

In this pic: the flexi joints are part of the front pipes which run into the mid section with the 2 secondary cats



I don't have many pics of the euro 2 2.5 manifold but this is it in place behing a heat sheild unfortunately.



And again (rear bank) 2.5 euro 2 manifold.



And in this pic - GTA engine with Euro 3 manifold in place:

fao PeterK

(my message box is full)

If your car was post 2001 euro 3 then it will have had the same manifolds as a GTA.

If it was pre 2001 i.e. Euro 2, they've changed the manifolds to euro 3 spec.

But then you live in germany anyway so all of that could apply to the uk anyway.

Non cat manifolds are not compatable with the GTA/euro 3 down pipes without some substantial modification.

hmm..cheers Chris..

I guess the Q for me is how do i spot the difference between Euro II and Euro III manifold ?

If i understand it correct, then the Euro II manifold goes with the GTA front pipes. I definitely got the GTA front pipes, and GTA rest of the way.

Originally Posted by Peter K

I guess the Q for me is how do i spot the difference between Euro II and Euro III manifold ?

The Euro3 manifolds have a Cat in them.

Yeah i just had a look, there is a cat in the manifolds on my car. For a moment there i thought they were in the front pipes from Chris's description.

So we are back to the problem of the euro II manifolds not fitting the Euro III engine? I know someone who tried to fit on to a GTA and ran into problems. How did you manage that Chris?

I've got a complete euro 2 system on mine:

2.5 manifolds and front pipe, a decat and a stainless mid and rear box.

do you reckon there is a gain in power in using the euro2 setup?

and is it compatible with the gta centre section and backbox?

Originally Posted by pablo

do you reckon there is a gain in power in using the euro2 setup?

and is it compatible with the gta centre section and backbox?

Possible power gain.


re centre section: NO!!!!!!!!!!!! Why you no listen?

by centre section i mean the bit between the sec cats and the backbox. did you mention that?

Originally Posted by Peter K

So we are back to the problem of the euro II manifolds not fitting the Euro III engine? I know someone who tried to fit on to a GTA and ran into problems. How did you manage that Chris?

I don't know about 2.5 Euro II manifolds but you can fit 3.0 Euro II manifolds to a 3.2 V6 engine without much fuss. My mechanic just did it to his GT 3.2. From what he told me, should you decide to do it you will get a slight drop of power in the low rev range and an increase in the high rev range. Also you will get a metallic rattle from the exhaust, meaning that you will probably need a new tailpipe that sounds better.

Originally Posted by pablo

by centre section i mean the bit between the sec cats and the backbox. did you mention that?

I know which bit you mean. No it won't fit.

With the possible exception of the rear box any part of the euro 2 system off a 156 v6 is NOT compatable with a euro 3 system, off a GTA or a 2.5....