Stock exhaust help h

[G-olf]

I suspect a stainless silencer would be close to that without fitting.

If you buy the standard centre it should just need the sleeve clamp on downpipe end and a regular u bolt type for the joint to back box.

As JB said, just run the car into the mot station and ask them to put it on the emissions machine to see if your cat has done the job.  Make  sure car is warm/ oil temp is high enough so the cat has enough heat in it.

[Jons1001]

Cheers, yes i will call in the mot centre this weekend and ask if they can test emissions before mot or if not first thing as part of mot. If cat is no good I'll probably throw more money at a standard downpipe (which equals even more as map will probably need changing). Failing that may see whether the tester likes £20 notes.

Thought i had an alright deal by knocking off £500 asking price to sort the exhaust but current cost £210, plus silencer, plus potential remap @ £££ and i still don't know if it will pass an mot!

What are people's opinions on what the sound should be like with 3" downpipe and sports cat into standard middle silencer and rear, surely still not going to be mega loud?

[G-olf]

Lots of people on here have that combo, it should be just a bit louder than standard.

They always make more noise on cold start, then settle down.
You’re probably getting a bit of extra induction noise because of the filter too

If the tuners map is the same for sports cat or de cat then it should be ok. Something to perhaps check out once you’re up and running

[Jons1001]

Lots of people on here have that combo, it should be just a bit louder than standard.

They always make more noise on cold start, then settle down.
You’re probably getting a bit of extra induction noise because of the filter too

If the tuners map is the same for sports cat or de cat then it should be ok. Something to perhaps check out once you’re up and running

Cool, i could live with that level of noise. Yeah I'm unsure on the map, they said they'd want £150 to tweak the map but didn't say in what way it needed to be tweaked. If it's just lost a few bhp then i don't care but what I don't want is it to damage the car in anyway obviously or cause it to use more fuel etc. Another more local tuning company with great reviews said they can't see why it would need altering.

[ahsan82]

have you thought about taking it to a custom exhaust place to have a centre box added to reduce the noise?

[fakie1977]

have you thought about taking it to a custom exhaust place to have a centre box added to reduce the noise?

Yeah this is what I would do - getting someone to add a resonator/silencer shouldn’t be that expensive.


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[Jons1001]

have you thought about taking it to a custom exhaust place to have a centre box added to reduce the noise?

Yeah this is what I would do - getting someone to add a resonator/silencer shouldn’t be that expensive.


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Do you mean getting a resonator/silencer welded in where the OEM one would be? What would be the reasoning behind this over OEM, better sound/less restriction etc.? If it was nearly as cheap then I would go for it but I'm looking at £80 for new centre silencer fitted. The exhaust company that quoted to weld in my CAT wanted £150 and that's with me supplying the part so I'm guessing it will be the same for a silencer plus the part so looking at £250?

[pudding]

The original system is 63.5mm I think.

I'm sure I measured it at 70mm outside diameter last time I messed with the exhaust. I could be wrong though, was a while ago. Ze Germans love their odd ball metric sizing.

It's a strange system.  Massive turbo outlet, which then immediately throttles down into a tiny crimped section for gear cable clearance after the cat, and then bores up again to 70ish mm back, and then squashed down again for floor/subframe clearance at the back.

Having said that, I've not noticed a 'seat of the pants' gain in fitting a 3" downpipe.  Maybe 10hp at the top end, tops.  In spite of the physical evidence and intuition of restrictions and narrow bore....the net result isn't actually that restrictive.  Voodoo gas flow dynamics at play.  Plus the engine is physically and electronically tuned for said restrictions.  In the same way binning the R32's cats absolutely kills the bottom end torque.

[pudding]

Lots of people on here have that combo, it should be just a bit louder than standard.

They always make more noise on cold start, then settle down.
You’re probably getting a bit of extra induction noise because of the filter too

If the tuners map is the same for sports cat or de cat then it should be ok. Something to perhaps check out once you’re up and running

Cool, i could live with that level of noise. Yeah I'm unsure on the map, they said they'd want £150 to tweak the map but didn't say in what way it needed to be tweaked. If it's just lost a few bhp then i don't care but what I don't want is it to damage the car in anyway obviously or cause it to use more fuel etc. Another more local tuning company with great reviews said they can't see why it would need altering.

As per my comments in your other thread, you don't need a map tweak to fit a sports cat in terms of engine performance.  It will tune itself automatically for mild alterations like that.  What they might mean is turning off the downstream O2 sensors to stop the EML coming on.  That is a simple on/off byte change in the map, hardly £150 worth of work. 

The reason why the EML might come on with a sports cat or decat is because gas flow through both is much faster compared to an OEM cat, which the secondary O2 detects as a catalyst efficiency fault and stick the engine light on the dash.  The best thing to do is run the sports cat for a while and see if the EML comes on.  If it doesn't, all good.  If it does, worry about shifting the EML some other time.  It doesn't do anything to the engine.  It's just an EU emissions law to flag a cat fault.

[Jons1001]

Lots of people on here have that combo, it should be just a bit louder than standard.

They always make more noise on cold start, then settle down.
You’re probably getting a bit of extra induction noise because of the filter too

If the tuners map is the same for sports cat or de cat then it should be ok. Something to perhaps check out once you’re up and running

Cool, i could live with that level of noise. Yeah I'm unsure on the map, they said they'd want £150 to tweak the map but didn't say in what way it needed to be tweaked. If it's just lost a few bhp then i don't care but what I don't want is it to damage the car in anyway obviously or cause it to use more fuel etc. Another more local tuning company with great reviews said they can't see why it would need altering.

As per my comments in your other thread, you don't need a map tweak to fit a sports cat in terms of engine performance.  It will tune itself automatically for mild alterations like that.  What they might mean is turning off the downstream O2 sensors to stop the EML coming on.  That is a simple on/off byte change in the map, hardly £150 worth of work. 

The reason why the EML might come on with a sports cat or decat is because gas flow through both is much faster compared to an OEM cat, which the secondary O2 detects as a catalyst efficiency fault and stick the engine light on the dash.  The best thing to do is run the sports cat for a while and see if the EML comes on.  If it doesn't, all good.  If it does, worry about shifting the EML some other time.  It doesn't do anything to the engine.  It's just an EU emissions law to flag a cat fault.

Thanks this is reassuring. The light didn't come on the other day when I had it fitted but I didn't run the car for very long at all. Because they had mapped out the eml with the decat you would think it would come on with the sports cat either.

Now my other problem is the noise! Do you think putting the middle silencer back in will make a big difference? Watching YouTube I can't make up my mind. Even peoples videos where they have same as me (3 inch decat/sports cat into middle delete into standard backbox) it just doesn't sound as raw as mine, it has at least some tone to it where as mine is just LOUD. And it def. Isn't leaking either. Will have to try and do a video to see what people think.

Some people mention having a silencer put in, still not sure if they mean welded in or those things you put in the exhaust tips? Any further advice welcome, main aim is to reduce noise significantly while having a little effect as possible on the map. And all for the cheapest price possible, not asking much am I 

[brian_badonde]

Best bet is to go to a decent exhaust place and ask for their opinion I think. A middle silencer/resonator will definitely make a difference, hard to say by how much. What back box is on there at the moment? Is it the stock one? My (limited) understanding is that the back box is there to primarily reduce the overall volume whilst the resonator aims to avoid resonant frequencies that give you a drone in the cabin, although obviously as they're another restriction they also reduce volume.

[Jons1001]

Best bet is to go to a decent exhaust place and ask for their opinion I think. A middle silencer/resonator will definitely make a difference, hard to say by how much. What back box is on there at the moment? Is it the stock one? My (limited) understanding is that the back box is there to primarily reduce the overall volume whilst the resonator aims to avoid resonant frequencies that give you a drone in the cabin, although obviously as they're another restriction they also reduce volume.

Hi mate, yes it's the original backbox. I've ordered the standard middle section so hopefully get that fitted later this week. I've taken a video today but not sure how I post it. Worryingly lots of black smoke on first rev but I'm hoping that's just where it's been sat for weeks as it didn't smoke before.

I've booked it in for an emissions test tomorrow at my mot place so crossing fingers it will be ok.

[Jons1001]

https://streamable.com/tnucue

Try this, black smoke is bad! But like I said this was the first time I started it in a week or two and also since the new downpipe was put on (only ran it for a few minutes when fitted). Hardly revved it either as I didn't want to upset the neighbors.

[G-olf]

Don’t forget they always make more noise on cold start it will settle down as it warms up.

Black smoke may just be lots of stop/starts?? Fuel??

Who welded in the sports cat and did they do a good job? How much was it?

Interested to see how you get on with emissions test.

Good luck 👍

[Jons1001]

Don’t forget they always make more noise on cold start it will settle down as it warms up.

Black smoke may just be lots of stop/starts?? Fuel??

Who welded in the sports cat and did they do a good job? How much was it?

Interested to see how you get on with emissions test.

Good luck 👍

Yes to be fair after a minute it was idling pretty quiet with no smoke. Hoping the black smoke is like you say stop starts rather than running rich/lean. It's been sat for weeks now with only odd start, not driven.

The cat was welded in by a bloke working out of his front garden in the roughest area of town lol. He did have excellent reviews online and was cheap at £60. Wasn't entirely happy though as he didn't smooth off the end and so it wouldn't fit back together meaning my mechanic had to get the grinder out, cost me another £20. No leaks though once on.

Yes will update tomorrow, was thinking of putting some liqui moly in then taking it for a little run first, worth a try?