Colin747 Posted March 13, 2017 Share Posted March 13, 2017 In that case I'm off to throw my cats in the bin haha What test pipes do you have? They're Japspeed, but all decats are the same, they're either silenced or not silenced, mine aren't. Thanks, didn't know you could get silenced ones. Just one last thing, have you never had problems at the MOT with the tester noticing that the cats are physically missing even though it passes emissions? Link to comment Share on other sites More sharing options...
Wasso Posted March 13, 2017 Share Posted March 13, 2017 Even though the intentional destruction of the exhaust is after the cats, there is still a massive amount of carbon monoxide passing through. It's a question of whether it can actually enter the cabin through normal driving though. Most of it will disperse into the air anyway and (from watching a few vids) most of the exhaust still comes out the back. Yes it can. Recently had the tiniest of blows between a decat n y pipe. At traffic lights within seconds you could smell the fumes through the transmission tunnel. Got it sorted after a week. But couldn't drive it due to headaches and nausea it caused. My wife & dad also noticed it. I know a decat with increase fumes etc but still lol Man it's you health.... why risk it? This ^^^^^^^ Next time you're under your car take a look beyond the gearbox, and see what exactly separates you from from the road beneath. Take into account this is where your gear stick will enter the cabin. There's not a great deal of protection in this area, and rightly so as it's not susceptible to water ingress. What you'll be doing is literally venting a large proportion of your exhaust gases straight up via the gear stick. Yes it's post CAT, although do you really believe there's nothing still within those gases that won't affect you. Dude, this is not a good modification, and I get what you're saying about a cheap sound mod, but just go and get yourself a decent exhaust in line with a budget that suits your needs. If you cannot justify spending that sort of cash on a decent exhaust, then trying to kill yourself may just be the other alternative! Link to comment Share on other sites More sharing options...
Ekona Posted March 13, 2017 Share Posted March 13, 2017 Darwin in action 1 Link to comment Share on other sites More sharing options...
KyleR Posted March 13, 2017 Share Posted March 13, 2017 In that case I'm off to throw my cats in the bin haha What test pipes do you have? They're Japspeed, but all decats are the same, they're either silenced or not silenced, mine aren't. Thanks, didn't know you could get silenced ones. Just one last thing, have you never had problems at the MOT with the tester noticing that the cats are physically missing even though it passes emissions? I'm not sure the silenced decats make much difference but they do look like cats a bit This was the first time I've put a car through without cats. I would say it's down to the tester, you may get someone who will cause a fuss or you may not. Link to comment Share on other sites More sharing options...
Richf Posted March 13, 2017 Share Posted March 13, 2017 Link to comment Share on other sites More sharing options...
Jay84 Posted March 13, 2017 Share Posted March 13, 2017 The difficulty is the mot station is required by law to keep an emissions print out with the centres copy of the paperwork. Looking the other way wont be enough, theyd have to emissions test another car. I've heard of places doing this and getting away with it, and doing it and getting shut down. 1 Link to comment Share on other sites More sharing options...
Ekona Posted March 13, 2017 Share Posted March 13, 2017 Unless the equipment fails to record the data because of breakdown, then the operator enters a pass or fail manually. Allegedly. 1 Link to comment Share on other sites More sharing options...
Jay84 Posted March 13, 2017 Share Posted March 13, 2017 I know they can do that for brake readings and there is less of a paper trail then. I've heard of place probing a standard 350 to get a modified one through, some kid asked me if I'd do the same. In the end he bought a standard system and got us to fit it for him then put his AM one after it had passed. Link to comment Share on other sites More sharing options...
AliveBoy Posted March 13, 2017 Share Posted March 13, 2017 If you want your car to sound shite, just smash the core out of your cats, or drill some holes in the back box. Each of those methods will have the desired saxo effect and won't kill you. Link to comment Share on other sites More sharing options...
Strudul Posted March 13, 2017 Author Share Posted March 13, 2017 (edited) Right, although a few of you have provided some useful insight, and I appreciate the time everyone has taken to respond, the majority seem to have either not bothered to read the thread past the first line or there has been some miscommunication... There's a lot to reply to, but I'll just summarise everything into 1 response and hopefully you can all work out where I have addressed your concerns / points. So, to clarify: - The mod would be temporary for testing purposes. - I am fully aware of and explained the potential negatives in the OP. - The spacers would be installed at the flanges between the centre muffler / resonator and the backbox (next to the rear dif, under the middle-ish of the boot). - I know it won't sound as good as aftermarket, but the objective is purely increased noise Expanded version covering everything. (Please read this before replying to avoid a repeat of what's already been said.) Temporary I've stressed this multiple times, but it seems to have been ignored. This is purely a test to see what the extra noise is like to live with. It doesn't have to sound great and isn't intended to be a permanent solution. I can do it / undo it in 5 minutes (assuming the bolts aren't seized), so MOTs etc aren't an issue and it's a better option that drilling holes in stuff. Cheap As per the previous point, the idea would be to get a proper system based on the outcome of the spacer mod. I don't understand how cheap can factor into that. It's not cheap to trial something before you buy it, it's sensible. Let's put it this way, if you test drove a 350z that turned out to be really crap with loads of issues, but you liked it, then you're gonna love one in good condition with no issues. The crap one doesn't give a good representation, but it can provide enough information to make a better judgement. Location So far everyone who has commented about exhaust leaks and the dangers has referenced it being around the Y-pipe / de-cats, under the gearbox. This will not be the case, it is much further back, almost at the back of the car. I also have strong doubts about the ability of any fumes getting inside the car. If you are moving or there is any wind, surely the escaped fumes will be blown away (the same way they are normally). Unless you are going to start revving the engine while stationary in a garage, i don't see the problem. It's something to consider and be careful of, but I don't see it causing any problems. I can easily test it by running the car for a while and checking for fumes (smell / battery operated CO detector). Noise The noise doesn't have to be good, it just has to be louder than it is currently. That's not what I'm after eventually, but for now, as precursor to an upgrade to see if it would be a good idea or not, it just needs to be louder. If I don't mind how a loud crap sounding exhaust sounds, then I will know for sure I'll like a louder good sounding one. As for my comment on the spacers sounding similar to a cobra, I was comparing 2 videos (which probably don't do either setup justice). I'm not denying that they may sound massively different in reality, but from the videos, I couldn't notice much difference at all. Considering I'm much younger than most of you and will therefore statistically have much better hearing, I think my opinion is valid. Experience The amount of experience I have of the Z33 or cars in general is irrelevant. This is a technical question about exhaust systems where the requirements to understand it are physics / mechanical engineering oriented. It's for a car related discipline, but expertise in that area is not enough to give a fully informed answer and as such most of your opinions are just as valid as mine regrdless of how long you've been driving. We can all apply common sense and logic, as I did in the first post, but just regurgitating what I already said (when I covered the potential negatives, the reasoning behind them, and why they may not apply / be of issue in this situation) isn't actually adding anything to the discussion. Edited March 13, 2017 by Strudul Link to comment Share on other sites More sharing options...
Jetpilot Posted March 13, 2017 Share Posted March 13, 2017 Why do you refuse to believe the 100% who have said it will sound sh*t, it will give you NO bearing on whether louder is better as it in no way will sound anything like a straight through silenced exhaust, from cobra, milltek, invidia etc etc! It will sound like a blowing exhaust, nothing more, nothing less. 1 Link to comment Share on other sites More sharing options...
Strudul Posted March 13, 2017 Author Share Posted March 13, 2017 (edited) Why do you refuse to believe the 100% who have said it will sound sh*t, it will give you NO bearing on whether louder is better as it in no way will sound anything like a straight through silenced exhaust, from cobra, milltek, invidia etc etc! It will sound like a blowing exhaust, nothing more, nothing less. Why do you refuse to believe that just being louder is enough for me to make a better judgement? It doesn't have to sound good, it just has to sound like an exhaust, but louder. How many times do I have to state this before it will sink in? Also just about everyone who has done it has said they thought it sounded good (they may be bias / lying, but at least they have firsthand experience under the same conditions, which I'm assuming is more than just about all of you). (However, this is irrelevant as per the first paragraph.) Edited March 13, 2017 by Strudul Link to comment Share on other sites More sharing options...
Ekona Posted March 13, 2017 Share Posted March 13, 2017 It won't sound anything like how a louder exhaust will though. It'll sound like a blowing exhaust, which is 100% different in tone. How many times do we have to state this before it sinks in? 2 Link to comment Share on other sites More sharing options...
Jetpilot Posted March 13, 2017 Share Posted March 13, 2017 (edited) But it wont sound like an exhaust, it will sound like a blowing exhaust, worlds apart ffs, but fill your boots, snap as above as I typed. But go for it, perhaps try taking one up the b*m, apparently some people think thats good too Edited March 13, 2017 by Jetpilot 1 Link to comment Share on other sites More sharing options...
Strudul Posted March 13, 2017 Author Share Posted March 13, 2017 (edited) Is a blowing exhaust louder than one that isn't, yes or no? Edited March 13, 2017 by Strudul Link to comment Share on other sites More sharing options...
Will370z Posted March 13, 2017 Share Posted March 13, 2017 Seems like you have made your mind up to try it regardless of the feedback here. Not sure of the purpose of this thread currently except to prolong a debate that is going nowhere. If you are going to do it id say save your energy posting here and get on and do it and update us with the result. Link to comment Share on other sites More sharing options...
Ekona Posted March 13, 2017 Share Posted March 13, 2017 Is a blowing exhaust louder than one that isn't, yes or no? A Corsa with a 6" exhaust is louder than a stock 350z, but which sounds better? Do you see where we're going here? Yes, your test will be louder, it also won't give anything like a real-world idea of what a new exhaust will sound like. Let's pretend for one second it does though: So what? Let's assume you're happy with a louder exhaust, how do you propose to translate that into buying a new setup? Link to comment Share on other sites More sharing options...
Lexx Posted March 13, 2017 Share Posted March 13, 2017 As per Will. I'm am tempted to lock this thread down as it is just going round in circles and is frustrating all parties involved. 1 Link to comment Share on other sites More sharing options...
Ekona Posted March 13, 2017 Share Posted March 13, 2017 Can we leave for a second until he's answered the last bit of my last post please? Promise to keep it civil. Link to comment Share on other sites More sharing options...
Jetpilot Posted March 13, 2017 Share Posted March 13, 2017 Or here: www.barryboys.co.uk 1 Link to comment Share on other sites More sharing options...
Richf Posted March 13, 2017 Share Posted March 13, 2017 To be fair when my 350z started to blow at the rear flange where they all go , i really liked the sound of it :) 1 Link to comment Share on other sites More sharing options...
Strudul Posted March 13, 2017 Author Share Posted March 13, 2017 Seems like you have made your mind up to try it regardless of the feedback here. Not sure of the purpose of this thread currently except to prolong a debate that is going nowhere. If you are going to do it id say save your energy posting here and get on and do it and update us with the result. As per the OP: Can anyone weigh in with some solid advice? I wanted constructive reasoning backed up with real evidence and experience. In hindsight, it probably wasn't a very good place to ask as nobody here has the experience / qualifications to provide the answers I'm looking for. A technical / engineering / physics oriented board would have been a better option. That being said (and before I'm accused of it), it's not that I'm not getting the answers I want, I'd be just as sceptical if everyone said it was a good idea. Link to comment Share on other sites More sharing options...
Strudul Posted March 13, 2017 Author Share Posted March 13, 2017 (edited) A Corsa with a 6" exhaust is louder than a stock 350z, but which sounds better? Do you see where we're going here? Yes, your test will be louder, it also won't give anything like a real-world idea of what a new exhaust will sound like. Let's pretend for one second it does though: So what? Let's assume you're happy with a louder exhaust, how do you propose to translate that into buying a new setup? Irrelevant. For the 50th time, it's not about testing better sounds, just louder ones. So, for the purpose of this investigation, driving a riced Corsa would actually give me enough to go with to make a decision on whether to get a louder exhaust or not, but i don't have one of those. Different car, different noise, crap sound, but that's not what I'm trying to test for. I don't know how I can make it any clearer: - It doesn't have to sound good - It doesn't need to have a similar tone to an aftermarket solution - It just needs to be louder I translate my like / dislike of a louder noise into knowing whether I want an aftermarket system or not. It doesn't tell me which, or how loud, or what tone I'm after, just whether louder is acceptable. Edited March 13, 2017 by Strudul Link to comment Share on other sites More sharing options...
Strudul Posted March 13, 2017 Author Share Posted March 13, 2017 To be fair when my 350z started to blow at the rear flange where they all go , i really liked the sound of it :) This is probably one of the most useful replies in the entire thread... Link to comment Share on other sites More sharing options...
Ekona Posted March 13, 2017 Share Posted March 13, 2017 Tone is vital though, much more vital than simple volume. If you have two exhausts of equal volume but one sounds rough as hell or drones at certain revs, you'll absolutely hate it. It's why companies spend a fortune in sound tuning, not just volume. You would have a much more useful comparison if you arranged a mini meet of 4 or 5 cars and spent 10 mins passengering in each. Let's assume you do like it louder, which exhaust would you go for? How would you make that decision? Link to comment Share on other sites More sharing options...
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