Strudul

Doesn't cool down much having gone through the y-pipe and centre muffler? The leak is coming out just before the backbox...

Didn't have much experience of it at a consistent rpm though and any annoying drones it may have produced. Was always flying through the revs and didn't go on any long motorway journeys where it may have started to irritate me.

have you just shot yourself in the foot ? No, because as per the previous posts, I understand that and can keep that in mind when making a decision. It goes to show that volume and tone are different factors and should therefore be judged separately (enforcing my point, not contradicting it).

It would have to be tested under a variety of conditions for a prolonged time. 10 minutes would be enough to get an idea, but I think longer would be beneficial. This is where the 350Z experience and the reason for asking here comes into play. Some of you know the car very well and might know exactly what is in the vicinity and could be damaged by heat. Are you sure on that 500°C figure? (as per the OP) I read a few places that said it wasn't that hot and they could leave their hand nearby without it being uncomfortable. A CO sensor and dropping a window should keep it safe, but I'm still not sure I understand how it gets in... Stationary, yes, but moving??

I've considered both... 1. That research would include finding out whether it drones and at what rpm (based on feedback / ride-alongs) 2. I know I thought about this, but can't remember if I wrote it down. Yes, it doesn't quite work if I hate it as an aftermarket option may still be viable, but I just have to keep this in mind when making a decision. It might not work, but I can only see it helping in making a decision. Knowing what's bad can make what's good more obvious. The only sporty things I can relate it to (off the top of my head) from real life experience (being inside and specifically listening to the exhaust) is an F-type R, F-Pace S, 350Z HR, Civic Type-R FN2, A5, Focus ST Mk3. All of which were stock. F-Type R was the loudest, but didn't sound too loud. I did prefer the active exhaust turned off, but not due to volume, I just preferred the tone.

Which is why I was hoping for factual answers about: - anything nearby which could be damaged by the heat (wiring?) - what sort of temperatures to expect and whether these are high enough to cause damage (it's been reported that it's not actually hot and isn't anything to worry about) - ways to keep the temperates to a minimum to avoid the above (don't rev too high for prolonged periods?) - how likely it is for fumes to get in based on the location of the leak (it's right at the back under the boot) - ways to avoid fumes getting in (don't leave the engine running when stationary for prolonged periods, open a window) It's purely matter of opinion whether a louder exhaust would work and which one is best to suit your needs. The same way I (and many others) don't want lowering springs while other people are happy to slam their car, but some people are happy with open headers, Not sure where you got a year from, I'm talking couple days consisting of trips of maybe 30 minutes each.

Which is why I'm not just seeing if I can stand listening to Justin Beiber at full blast for an hour. If I'm reasonably content with a louder blown exhaust, then I can use that to determine which parts I like / don't like and then find out which aftermarket systems do / don't have those features. Get opinions, read reviews, and eventually try passenger rides. It's not ideal, I know, but I reckon it will help.

That would be a better solution, but: - I'm not sure 10 mins would be enough time - The results will vary depending on road surface, music volume etc - I'm not sure passenger / driver perceptions would be the same (driver has other things to focus on which impair hearing*) - I don't want to waste people's time or fuel - I don't know if anyone local has aftermarket systems, never mind a good variety *The same way blind people have better hearing and you can hear better if you close your eyes. Yes, the spacers won't help me choose which exhaust, but it gives me more to go on than I currently have and I believe would aid the decision making process doing as you mention (being a passenger).

This is probably one of the most useful replies in the entire thread...

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.

As per the OP: 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.

Is a blowing exhaust louder than one that isn't, yes or no?

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.)

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.

Thanks to everyone that came. Bit of chaos parking, but was pretty succesful overall with a decent turnout (6). Didn't take any pics, but a few of the others did and I'm sure Scot will get some up soon.

Main car park is full se we are in the overflow ( turn right towards J32 instead)

I'm no audiophile, but it sounds pretty similar to a Cobra to me (minus the crackles)...

I'm aware of this (as mentioned in the OP), but it sounds like the closest you can get... It won't determine which aftermarket exhaust to get, but will help decide if it's something I want to pursue at all. Ignoring the fact its an exhaust leak and done by some kid, can you honestly say it doesn't sound 1) good and 2) like an aftermarket exhaust?

That's not even close to being the same... The sound difference between running no airbox or an aftermarket exhaust is beyond huge, and I'm not trying to test what an aftermarket intake would sound like... No airbox / filter will almost definitely result in leaves and crap getting sucked in and causing damage. However, nobody seems to be able to say the same about an exhaust spacer, it's just potential problems that probably won't happen, but might, and even if they do it's reversible in 5 minutes...

Thanks, this is the kind of response I was hoping for. Other than location and distance of pipe, is it really any different to just straight piping after the Y-pipe? Does that extra few feet of pipe really make that much difference? Bit of a stretch, but the SLR exhausts come out behind the front wheels...

Unless the leak is intentional and controlled for a desired purpose with a clear understanding of the extent of any potential issues...

Wouldn't a 1/8" gap be a much smaller hole than your exhaust tip and therefore the chance of air going back through be minimal?

Wasn't being serious about that I gave the exact same reasons not to do it in the OP, nobody has actually added anything I didn't already know or given any evidence of them being a cause for concern. I'm not claiming I know better or that you are all wrong, I'm just saying that nobody actually seems to know, everyone is just making assumptions. If you don't know the answer for definite, then by definition it's ignorance (lack of knowledge) and speculation (a theory without firm evidence). It's not meant as an insult, just an observation... Is it a good idea, probably not, but if nobody can prove that it's a bad idea, I don't see the harm in trying it...

What would help more so is an explanation of how the air goes back in. What stops it going back in normally? There's still a hole, it's just at the end, all it does is move the end forward... And doesn't the exhaust pressure pushing back stop the air from going in (the same was you can light a gas tap and the fire doesn't spread through and cause the tank to explode). The leak is so close to the exhaust tips that I can't see how it would cause any drastic problems.