Decat - More noisy?
Discussion
I have a 91 Eunos 1.6 with a generic stainless cat-back JDM exhaust on. I'm thinking about de-catting it because a)I think its knackered b)I want to increase my carbon footprint c)It doesn't legally need one anyway. Will it be noticably louder with just a straight pipe?*
Has anyone done this to theirs? I can't stomach spending £60 on what is effectively a piece of straight exhaust pipe so I'm going to try and find a friendly local exhaust merchant to remove the cat and weld a piece of pipe in, any idea's of what this should cost? Someone mentioned that I could just take the cat out, beat its innards out and then stick it back on, good idea or not?
Has anyone done this to theirs? I can't stomach spending £60 on what is effectively a piece of straight exhaust pipe so I'm going to try and find a friendly local exhaust merchant to remove the cat and weld a piece of pipe in, any idea's of what this should cost? Someone mentioned that I could just take the cat out, beat its innards out and then stick it back on, good idea or not?
- Secretly, I want it to be louder and raspier, because I'm still a boy racer deep down...
Moss Europe do a really nice decat section that bolts in as a direct replacement to the cat - part number MXV1265. Buy new front and rear gaskets also (different sizes each end) and just bolt in place, I used some high-temp silicone also.
I've got one on mine, as well as an MX5parts high-flow downpipe and it's much much louder, and I've not yet been beyond 4000rpm as I'm running in the engine.
Coupled with a twin stainless tailpipe should be an excellent noise.
http://www.moss-europe.co.uk/Shop/ViewProducts.asp...
I've got one on mine, as well as an MX5parts high-flow downpipe and it's much much louder, and I've not yet been beyond 4000rpm as I'm running in the engine.
Coupled with a twin stainless tailpipe should be an excellent noise.
http://www.moss-europe.co.uk/Shop/ViewProducts.asp...
Looks nice, but the whole ethos of my Eunos has been budget budget and more budget, seeing as the thing only cost me £600 and I use it once a week at most. I'm loathed to pay £50 + VAT and shipping for a piece of straight pipe that I could get with a hacksaw and a piece of old exhaust.
OllieWinchester said:
Looks nice, but the whole ethos of my Eunos has been budget budget and more budget, seeing as the thing only cost me £600 and I use it once a week at most. I'm loathed to pay £50 + VAT and shipping for a piece of straight pipe that I could get with a hacksaw and a piece of old exhaust.
The decat pipe is more than just a straight pipe - it's got a bend in the centre to account for the differences in the cat's front and rear pipe angles (check them - they don't line up) and has thick flanges with bolt holes so you don't have to ruin any part of the existing exhaust - just drop out the cat and bolt in the decat pipe. You can then very quickly put the cat back on if you need it to pass the MOT.OllieWinchester said:
I have a 91 Eunos 1.6 with a generic stainless cat-back JDM exhaust on. I'm thinking about de-catting it because a)I think its knackered b)I want to increase my carbon footprint c)It doesn't legally need one anyway. Will it be noticably louder with just a straight pipe?*
Has anyone done this to theirs? I can't stomach spending £60 on what is effectively a piece of straight exhaust pipe so I'm going to try and find a friendly local exhaust merchant to remove the cat and weld a piece of pipe in, any idea's of what this should cost? Someone mentioned that I could just take the cat out, beat its innards out and then stick it back on, good idea or not?
How handy are you? the cheapest route is take your cat off and use a long screwdriver and a hammer and bash all the cat material out yourselfHas anyone done this to theirs? I can't stomach spending £60 on what is effectively a piece of straight exhaust pipe so I'm going to try and find a friendly local exhaust merchant to remove the cat and weld a piece of pipe in, any idea's of what this should cost? Someone mentioned that I could just take the cat out, beat its innards out and then stick it back on, good idea or not?
- Secretly, I want it to be louder and raspier, because I'm still a boy racer deep down...
I cant tell you how louder it will make your as I have a 3" pipe straight through to a back box which after a couple of rear box changes is not much louder than standard (the first box I had fitted was so loud it failed the MOT
) It's louder, and raspier (don't expect a throaty burble) - but I'd say it suits the car well.
Yes, it does have angles on it. Think mine was £40-50 from MX5parts, I ordered some gaskets too, but I think it actually came with them anyway.
I have also done the knock the middle out of the cat trick, on the MX6 that preceded my Eunos - similar effect, although you will tend to get a resonance with the empty chamber at certain engine speeds. Deper sound than the straight decat pipe, and of course, free.
Yes, it does have angles on it. Think mine was £40-50 from MX5parts, I ordered some gaskets too, but I think it actually came with them anyway.
I have also done the knock the middle out of the cat trick, on the MX6 that preceded my Eunos - similar effect, although you will tend to get a resonance with the empty chamber at certain engine speeds. Deper sound than the straight decat pipe, and of course, free.
Gave my decatted Eunos the first post-engine-rebuild bootful this morning and it sounds great, really much louder than the stardard car and much more farty, but thankfully not the Max-power bass boom I was dreading it might be.
If only I could afford one of those twin-tailpipe stainless rear systems....
If only I could afford one of those twin-tailpipe stainless rear systems....
I've just removed my de-cat pipe and replaced it with a cat. I also have a PX induction kit and the MX5Parts twin exit stainless.
With decat fitted the car is VERY loud. The poster who said there's a rasp is right. It sounds like a reverberating kinda noise at low revs and gives way to a deep howl further up the rev range. It sounds fabulous when you're hooning, but it does drone at humdrum speeds and whenever you accelerate. It alsoi sounds like its coming from the gear stick - that's where the noise is in the car - the pipe is directly below.
Ultimately it became too much for me because 90% of my driving is daily "sensible". I've now fitted a cat to the car and it makes a big difference. The deep drone at ~3k rpm and acceleration is now gone but I still get a great sound from the twin pipes at the back - and also a rather groovy induction noise that I'd actually never heard before due to the decat.
It would be quite difficult to just make up a bit of pipe I think because both ends are at an angle - ie they are not simple flat ends. Take a look under the car and you'll see what I mean.
With decat fitted the car is VERY loud. The poster who said there's a rasp is right. It sounds like a reverberating kinda noise at low revs and gives way to a deep howl further up the rev range. It sounds fabulous when you're hooning, but it does drone at humdrum speeds and whenever you accelerate. It alsoi sounds like its coming from the gear stick - that's where the noise is in the car - the pipe is directly below.
Ultimately it became too much for me because 90% of my driving is daily "sensible". I've now fitted a cat to the car and it makes a big difference. The deep drone at ~3k rpm and acceleration is now gone but I still get a great sound from the twin pipes at the back - and also a rather groovy induction noise that I'd actually never heard before due to the decat.
It would be quite difficult to just make up a bit of pipe I think because both ends are at an angle - ie they are not simple flat ends. Take a look under the car and you'll see what I mean.
On my Mk2.5 I have a Larini Sports cat (2.25"), Larini Sports midpipe (2.25" no resonator) and a Racing Beat Dual back-box. It's VERY loud - louder than any MX-5 I've heard other than a Mk1 with throttle-bodies and a straight-through exhaust. It's so loud in fact that I can't hear my supercharger at all below about 5k rpm 
Just been browsing on MX5Parts website. Surely I don't want this..... http://www.mx5parts.co.uk/product_info.php/product...
It says it is silenced? I don't want it silenced, I want it loudened......
It says it is silenced? I don't want it silenced, I want it loudened......
Um, I think I'm going to keep it and offer it for sale with the car whenever I get round to selling.
Mine is pretty much like this one only shinier:
http://cgi.ebay.co.uk/370mm-de-cat-test-pipe-mx5-e...
Mine is pretty much like this one only shinier:
http://cgi.ebay.co.uk/370mm-de-cat-test-pipe-mx5-e...
MX5-Lazza, you absolute legend. The last ebay one you found is 5mins away from me, and it ends Sunday night, so hopefully if I get it then it'll be fitted by Monday morning. Been scouring ebay for ages, can't believe that one slipped under the radar! How much difference between the noise of a straight pipe replacement and one like this.... http://cgi.ebay.co.uk/mx5-de-cat-pipe-stainless-eu...?
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