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Discussion Starter · #1 ·
Hi, ..... rite when looking under my ZR TD today i noticed that the pipe from the rear flange to the backbox was a slighly smaller diameter to the pipe going to it (i.e the staight through pipe). I should of noticed this earlyer but the back box was fitted before the straight through section.

Now here's my question. the original pipe work plus the straight through pipe is the original size, im gues this is 2.5" pipe work. But the back box has 2" pipe work on it, which i havn't noticed untill now.
Will the back box with the small diameter pipe, be substanially more restrictive than the origainal 2.5" pipe.
basically shodl i get a new back box
, or should i take it to say for example powerflow (i know some of you dont lie the place). And ge these to cut the smaller pipe off and weld on a new larger diamtere pipe eg. 2.5" or 3" diamtere pipe, this should only cost about £40 max as opposed to a new back box which would be £150+.
i hope that made sense


any thoughts
 

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I would probably say the best option would be to get a new backbox as cutting and welding new bits on here and there would in my opinion not give very good gains as they're just trying to make the best of what you've already got. This will never be as good as a purpose made performance exhaust.

Wingy777's backboxes are top notch and will give good performance gains. I would recommend them to anyone as i have the ZS system and are very impressed by the difference in the way the car drives.

Depends really on what your prepared to pay though, but hope you get the gains your after either way mate.

Cheers,

Phil.
 

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The rear box is deliberatly slightly restrictuve to keep the noise levels down. Also as the exhaust gases pass from front to back they cool and so take up less volume so you'll quite often find the rearmost pipework is smaller than the front most so it isn't as big a problem as people like to suggest. However when I made up a backbox for my 600, I used 65mm pipework and a 63mm box and it did make a difference, (I had to turn my ron-box down as it hit boost cut after I'd installed the new backbox). The original backbox was very restrictive (its the only silencer on a 600), and some of the pipework was less than 50mm I reckon.
If your current backbox is stainless then there is no reason why you can't have it modified to a larger diameter if the internal diameter already matches. If not then you are just moving the restriction from thje pipework into the box. Also if it isn't stainless then I'd not bother, I'd just get a whole new backbox made up from scratch, as the rest of the system is very good (well at least it is on the 600).
 

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Discussion Starter · #4 ·
Cheers. guys
my back box is stainless so might see what the inside diameter of the backbox is, if its 2.5" then i will get a new pipe made up from the rear of the back box, failing that i think i might have to spend a few more pennies on a new back box, its a bit of a shame really because my backbox is only 6months old but was put on before my staright through pipe so i did not reaaly pay much attention to the size of the pipework doh!
 
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