backbox = zero bhp gain, correct?

1. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

   #1 4th February 2010, 16:14

   Am I right in thinking that simply fitting a back box will result in no gain in bhp but will only serve to enhance the driving experience by making the car sound more sporty?
   
   I know its probably been covered many times before but could someone please explain the difference in exhaust parts to me as its all a bit confusing tbh.
   
   4 branch manifolds, difference between 4-2-1 and 4-1s?
   
   de cat? think this makes the car illegal and you need to put a cat back on for the mot?
   
   cat back? Im assuming this means that the cat stays on?
   
   straight through pipe? not sure about this one, same as decat?
   
   silencer? same as back box?
   
   not sure if theres anything else Ive missed.
   
   I would be greatful if someone could explain the difference between these parts, what they mean and which would be best to fit to my VTR, well soon to be VTR on saturday hopefully
2. Daniel09 Established Member Joined: Jul 2009 N.wales! Posts: 1024 slammed VTS

   #2 4th February 2010, 16:16

   you can free up osme revs with a deccnet full exhaust system maybee a few bhp. a 421 will rduce more power in the mid range, where as 41 will give me power in the higher rev range
3. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

   #3 4th February 2010, 16:22

   thanks for explaining mate.
   
   full exhaust system would comprise of what exactly?
   
   which would you/do you prefer between a 4-2-1 and a 4-1?
   
   cheers
4. Daniel09 Established Member Joined: Jul 2009 N.wales! Posts: 1024 slammed VTS

   #4 4th February 2010, 16:26

   for road use, just buy a 4-2-1 but tbh, you wont see much gain in just normal everyday driving, maybee on a country road you will see it frees up the revs alot. a full exhaust system is manifold - centre section - and back box, some have a sports cat included in there aswell.
5. Jo3fish Established Member Joined: Jul 2009 Newcastle Upon Tyne Posts: 1267 03 EP3

   #5 4th February 2010, 16:27

   Quote:

   Originally Posted by 1ntense Am I right in thinking that simply fitting a back box will result in no gain in bhp but will only serve to enhance the driving experience by making the car sound more sporty? I know its probably been covered many times before but could someone please explain the difference in exhaust parts to me as its all a bit confusing tbh. 4 branch manifolds, difference between 4-2-1 and 4-1s? de cat? think this makes the car illegal and you need to put a cat back on for the mot? cat back? Im assuming this means that the cat stays on? straight through pipe? not sure about this one, same as decat? silencer? same as back box? not sure if theres anything else Ive missed. I would be greatful if someone could explain the difference between these parts, what they mean and which would be best to fit to my VTR, well soon to be VTR on saturday hopefully

   Correct, no bhp increase, but a nicer sound (depending on backbox)
   
   There are normally 3 pieces to an exhaust, starting from the engine and working backwards:
   
   Manifold: This is the first section of the exhaust (and normally quite restrictive), the difference between 4-2-1 and 4-1 is simply the number of tubes as you follow the manifold from the engine block to underneath the car to the centre pipe. It starts with 4 (4 cylinders - 4 pipes) and then they gradually move closer together as they move down either merging into 2 pipes then into 1 or straight into 1. And where it merges into 1 pipe you fill find a flange which fits onto the centre pipe.
   
   Centre pipe: typically the location of the Cat and silencer on most cars (some have the cat in the manifold) it connects the manifold to the backbox, de-cat'ing/silencing the centre pipe (buy buying a straight through) will help your engine breathe better (get the exhaust fumes out faster) however will increase your cars emissions dramatically thus making it an MOT fail.
   
   Backbox: Last but not least the backbox (also referred to as the rear silencer or the tail pipe. Its all the same, these typically define the sound of your car (raspy like the supersprint race backbox, or deep and 'purry' like the magnex) (orr, massively loud and evil if you get a 5" jap can ) the sound of your car doesn’t completely hinge on the backbox however it does have the largest effect (imo).
   
   The term 'cat-back' is typically used to describe a system, and typically means centre pipe and backbox. when selling a supersprint race cat back system, it means the supersprint race pipe and race backbox. It doesn’t actually identify if the cat is still intact or not.
   
   Silencer is not always the backbox, sometimes it can be referred to as the "rear silencer" however no always, some cars have a silencer in the centre pipe which reduces the noise of the exhaust.. hence the name.
   
   straight through pipe, referring to the centre section, means that it has no silencer or CAT.
   
   Hope that made things clearer for you mate
   
   Joe
6. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

   #6 4th February 2010, 16:44

   thanks joe, was definitely a big help
   
   me being not very good with mechanics (havent got a clue) it probably wouldnt be the best idea to get a de cat or straight though centre pipe as I wouldnt know or have the means to change it back come mot time, not sure how much it would be for a mechanic to change it back?
   
   how much would I expect to pay to get a back box or full system fitted by a mechanic?
   
   I take it its possible to get a manifold, leave the standard centre pipe and also fit a back box then?
   
   Ive watched and listened to a few clips on youtube with supersprints and like the sound they produce, can only find one clip of the kam racing one though which for some reason Im drawn to.
   
   Any real world difference between a race exhaust and a 'normal' performance exhaust? ie magnex, pipercross etc etc?
7. Jo3fish Established Member Joined: Jul 2009 Newcastle Upon Tyne Posts: 1267 03 EP3

   #7 4th February 2010, 16:56

   Quote:

   Originally Posted by 1ntense thanks joe, was definitely a big help me being not very good with mechanics (havent got a clue) it probably wouldnt be the best idea to get a de cat or straight though centre pipe as I wouldnt know or have the means to change it back come mot time, not sure how much it would be for a mechanic to change it back? how much would I expect to pay to get a back box or full system fitted by a mechanic? I take it its possible to get a manifold, leave the standard centre pipe and also fit a back box then? Ive watched and listened to a few clips on youtube with supersprints and like the sound they produce, can only find one clip of the kam racing one though which for some reason Im drawn to. Any real world difference between a race exhaust and a 'normal' performance exhaust? ie magnex, pipercross etc etc?

   By the sounds of things (to be most cost effective in the long run) is to get a performance exhaust which will fit on the OEM (standard) hangers.
   
   The best reccomendation i can give you is this:
   
   Click here
   
   IRC it fits on the OEM hangers so all you literally have to do is take the 2 bolts which hold the centre pipe onto the manifold then take the centre pipe and backbox off the hangers (literally just lift them off the hangers).
   
   A garage shouldnt charge more than 1hrs labour (however much that is at your local garage) to swap the 2 over.
   
   Unless your vtr is from year 2000 or newer this will decat and desilence your exhaust system (because from 2000 onewards the vtr's have the CAT in the manifold, so you would need to replace this to de-cat)
   
   You could fit a manifold and a backbox with a std centre pipe, but it wouldnt be logical. Most people get a cat back system.. then save up for a manifold.
   
   Most people worship the above exhaust system ive linked you too, its VERY popular on sax-p, not too loud and very raspy , its what you would be reccomended to get from most people on sax-p.
   
   And more questions.. just ask
   
   Joe
8. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

   #8 4th February 2010, 17:22

   thanks mate, thats pretty much the one I was looking at.
   
   cant find any clips that let me hear it first though, dont really want to order it without hearing it in action first.
   
   there seems to be lots of supersprint systems on youtube, only one with kam racing, its the centre pipe though with a supersprint back box.
   
   Ill have a look in the video section on here to see if I can find any.
9. user_16990 Frequent Poster Joined: Jul 2007 Posts: 810 2001 VTS

   #9 4th February 2010, 18:24

   I saw a 1.8 Bhp increase with a Magnex cat back over the standard Citroen effort. There are gains to be made, but pretty much on the small side.
10. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

    #10 4th February 2010, 19:27

    surely its not all about bhp gains though is it?
    
    the car will 'feel' faster with the enhanced engine sound.
    
    if a manifold frees up revs, even if for arguements sake, the engine sounded the same, would that not make the car feel faster in itself?
11. LeeM Saxperience Post Whore Joined: Feb 2008 Liverpool Posts: 7393 Black Corsa C SRi

    #11 4th February 2010, 19:51

    get a supersprint cat back, best you'll get while keeping it legal
12. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

    #12 4th February 2010, 20:20

    can I ask why?
13. LeeM Saxperience Post Whore Joined: Feb 2008 Liverpool Posts: 7393 Black Corsa C SRi

    #13 4th February 2010, 20:31

    proven gains, pretty cheap, lightweight and sound good. if your cats in the mani your only option is a decat or sportscat, and sportscats arent worth the money
14. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

    #14 4th February 2010, 21:45

    to decat it, I would have to get a new manifold though, correct?
15. Jo3fish Established Member Joined: Jul 2009 Newcastle Upon Tyne Posts: 1267 03 EP3

    #15 4th February 2010, 21:47

    Quote:

    Originally Posted by 1ntense to decat it, I would have to get a new manifold though, correct?

    what year is your saxo?
16. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

    #16 4th February 2010, 22:13

    It will be a 2001 on a Y Plate.
17. LeeM Saxperience Post Whore Joined: Feb 2008 Liverpool Posts: 7393 Black Corsa C SRi

    #17 4th February 2010, 22:38

    yes new mani is needed to decat
18. Veets L-plater Joined: Jul 2009 Doncaster Posts: 91 1st car Fiat Punto 60s Mk1 2nd car Saxo vtr mk2

    #18 4th February 2010, 22:48

    but to decat it wud make it fail m.o.t?
19. Lp12790 Regular Poster Joined: Jul 2009 Oxford Posts: 327 Peugeot 206 GTI 180, Citroen Saxo VTR

    #19 4th February 2010, 23:03

    yeah a decat would make it fail the mot
20. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

    #20 4th February 2010, 23:08

    would the mechanic doing the mot put the standard mani back on, sort the mot then put the decat mani back on though?
    
    suppose it depends on the mechanic, obviously you could always take it to a different mechanic to swap manis before and after the mot or do it yourself if you're able to.
21. Lp12790 Regular Poster Joined: Jul 2009 Oxford Posts: 327 Peugeot 206 GTI 180, Citroen Saxo VTR

    #21 4th February 2010, 23:18

    not if they were legal. they would pass a cars emmisions and then decat it.
22. 1ntense Regular Poster Joined: Sep 2009 Northants Posts: 296 VTR

    #22 4th February 2010, 23:26

    not sure I know what you mean mate?
23. col101 Frequent Poster Joined: Mar 2009 York Posts: 768 VTR

    #23 5th February 2010, 12:24

    Swapping the manifold for an mot and back again is not complicated, but it is time consuming. Expect at least an hours labour each side of the mot.