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Thread: exhausts....catback???

  
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    exhausts....catback???

    im been thinking about getting an exhaust manifold but i want to keep it legal and not loud...just a bit of a grumble maybe....tbh i just looking for a bit better performance dont want to stand out with a stupidly loud exhaust...so my question is can someone explain this exhaust situation to me.

    i have a peco catback exhaust so does this mean i dont need a cat at the front, thus being able to fit a manifold?? also if i done this to quieten it would i be better fitting a centre silencer??? im actually pretty confussed with all the options....

    any help cheers j

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    A manifold doesn't really add any noise tbh.... well not when i fitted one to one of my old cars any way lol

    cat-back just means you got an exhaust from the back of the cat. so you alread still got it on there a manifold does increase something though! (it was fitted to my 1.2 corsa)
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    i still dont get it lol......silly me....so i dont need my cat at the front then??? so dopes the back box contain a cat aswell???? i really donrt get it

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    Catback is just that - everything from the cat backwards leaving the cat in place. Changing the exhaust manifold usually requires you to replace the cat as well (which legally you need if there was one there already) but this depends entirely upon what you buy.

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    The cat is your centre section, which if you want you can upgrade to a sports cat. The first cat in the front is called the pre-cat which you dont legally need because it is only in use while the engine is cold, once it warms up the main cat is used so you can get rid of that if you want and still get it through MOTs as they are required to test you when your engine is warm. The back box is just exactly what it says on the tin, there isnt a cat in it mate, just the box at the back of your exhaust and tailpipe, connects from the main cat. Hope that explains it
    Driving Audi TT 225 Q

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    Nope, the cat is not the centre section, unless we're getting terms mixed up. The big box on the exhaust centre section is a simple silencer, same for the box on the backbox. The cat is usually on the exhaust manifold.

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    Layout of an exhaust system to makes things clearer

    Manifold - Cat - Centre Pipe+box - Back box + tail pipe
    On some engines the CAT is wielded directly onto the manifold, on other cars it is separate like the example above



    A CAT back system = 3 + 4. If you want to change the manifold to one that doesn't have a cat, you will need to have a cat weilded into the exhaust after the manifold.

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    I was under the impression 2 and 3 were one peice... sorry.

    Hasnt an astra got 2 cats though, as i replaced my first cat with a pre-cat downpipe...? but still have the main cat.
    Driving Audi TT 225 Q

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    Quote Originally Posted by nickfearn View Post
    Hasnt an astra got 2 cats though, as i replaced my first cat with a pre-cat downpipe...? but still have the main cat.
    Only certain engines, like the 2.0T's, 1.6T (if thats what you did it on). 1.6, 1.8 only have a single cat.

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    Im getting confused reading this thread. I took my cat out on my car and middle section just leaving me with a backbox. this would fail m.o.t? and my cars a 1.6 8v petrol btw

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