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Back Box Help


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Hi there,

So I was thinking of putting a different back box on my fiesta to give it more of a rumble. Two things... I know I should do it properly and change the whole system but tbh I don't think it's worth the hassle since looking to change to an ST next year ... 2nd I have a k&n induction fitted which gives great sound from the front but I want a rumble from the rear too. I don't want anything too big or to loud? Been having a look around but not sure on which one .. Any suggestions ? Not looking for to pricey either?

Plus any instal guides? I have a rough idea but not 100 % with this car?

Once again any help is much appreciate !

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If you only replace the back-box on the exhaust, it may not make that big a difference because the rest of the system is the same, for example, the system may only be 2" (50mm) also, the most restrictive part of the exhaust is often the catalytic converter, to really get a significant gain, you would probably have to replace the entire exhaust with a performance one (not cheap), and a sports/ perfformance catalytic converter as well, even then, realistically you are probably looking at a real-life 10% performance gain

However, if you just want to make a bit more noise this is easy to do, you could take a big metal spike and hammer a hole through the baffles in the silencer - this will make it louder

Or fit a "straight through" silencer -

pic 1-


pic 2


(its called a "straight through" silencer because the gas flow goes straight through it /you can see straight through it (pic 1) this type of sylencer will cut the high frequencies down but allow much of the lows through, sound-wise, and really help the flow/revs/power - it its the only silencer in the exhaust system may be a bit loud,(you may require another silencer too/ 2-straight through silencers are less restrictive than 1 baffle-type) though the cat cuts noise down a bit)

Hear are some pipes

this -


or this -


Piper (well known, quality brand/ still a lot cheaper than the Scorpion) -


or a single pipe -


edit - proper stainless- steel (304 aircraft grade/ iso9001) Miltek cat- back exhaust, (single 90mm jet)specifically designed for the mk6 fiesta (04-08) its has a 60mm diameter, its £381 but its a complete cat- back system -


Its easier to fit an exhaust/ back box rthan you might think - did you fit the K&N/ cool air intake (i like!) in your avatar? if so i would not think you would have a problem fitting the back-box :)


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Thanks for all the great info and all the links for all the links will have a good look through all of them and see what would suit my needs!

I understand for full gains ill need to replace the whole system , but atm just don't think it would be worth the investment.

And yes - i sure did fit the k&n , didn't find it too hard just common sense really. Got basic car knowledge so the back box swap should be fairly simple.

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