The Exhaust Thread

[Tom B 44]

Sorry if this is the wrong place to ask... But does anyone know the size of bolts used on the exhaust? (Front pipe) and the pitch of the thread? Want to make sure I've got all the bits to tackle an inevitable snapped bolt!

[Tom B 44]

Fitted my Borla UEL today, quite please with the outcome! 

[Mark-in-Stoke 488]

Tomie uel, cobra overpipe, cobra hfc and Miltek full res

 

And a drive by

https://youtu.be/e1ssY6OGeg4

https://youtu.be/e1ssY6OGeg4

[Tom B 44]

What's the general opinion of using 'heat wrap' on manifolds and overpipes? I've read a couple of horror stories online but got to be less of a fire risk than running without insulation? Anyone using it?

[Deacon 1357]

5 hours ago, Tom B said:

What's the general opinion of using 'heat wrap' on manifolds and overpipes? I've read a couple of horror stories online but got to be less of a fire risk than running without insulation? Anyone using it?

I wouldn't run it. Someone from the sprint at Curborough used it on their Civic Type R it got wet and over time the manifold basically disintegrated. I'll try and find the picture.

[Deacon 1357]

This was the picture that put me off heat wrap!

[S18 RSG 429]

Surely that only applies to the material wraps? There are some high quality titanium weave wraps available these days which do the same job, but being that they are mostly metal, would surely disintegrate no quicker than the manifold itself.

[Deacon 1357]

It was the exhaust that disintegrated inside the wrap.

[S18 RSG 429]

Yeah, but surely just because it was, in effect, wrapped in a wet blanket because the material was more absorbent of fluids than metal.

A titanium wrap won't absorb fluid, so shouldn't be any worse than an unwrapped manifold.

[Rich 378]

I have a heatshield of sorts on mine; it's more of a heat blanket than a full wrap though. In theory it allows the exhaust to expand and vent heat without trapping it like a full wrap does, while still shielding the sump and and other engine components.

[Tom B 44]

2 hours ago, Deacon said:

This was the picture that put me off heat wrap!

Yeah that is worrying! Although id have thought with the exhaust being so hot it would dry out any material pretty quick? So wouldn't be sat in a wet blanket for very long... Ah I don't know! I'm more worried about frazzling something under bonnet and causing a fire rather than rotting the manifold, but obviously neither occurring would be better  hah. 

[DanJ 374]

Exhaust wrap is banned in lots of forms of motorsport, if you have an oil or fuel leak it can soak/accumulate in the wrap which is a much bigger fire hazard than the drip drip of the leak burning off or running off the manifold/exhaust.

In this day and age then non-porous heat shielding or ceramic coating are the only way to go in my opinion.

[Deacon 1357]

3 minutes ago, DanJ said:

In this day and age then non-porous heat shielding or ceramic coating are the only way to go in my opinion.

Agreed.

[Tom B 44]

1 hour ago, DanJ said:

 

Exhaust wrap is banned in lots of forms of motorsport, if you have an oil or fuel leak it can soak/accumulate in the wrap which is a much bigger fire hazard than the drip drip of the leak burning off or running off the manifold/exhaust.

 

In this day and age then non-porous heat shielding or ceramic coating are the only way to go in my opinion.

I didn't know that, in that case I think I'll avoid it. 

[long-gone 152]

I have the AVO catback which I kind of like (photos are my car on the Fensport website).

Toying with upgrading the manifold before a re-remap but wary of emissions come MOT time. I know nothing in life is guaranteed but are they typically MOT friendly? Also don't want any more volume; it's loud enough as it is.

[S18 RSG 429]

16 minutes ago, daidaiiro said:

I have the AVO catback which  kind of like (photos are my car on the Fensport website).

Toying with upgrading the manifold before a re-remap but wary of emissions come MOT time. I know nothing in life is guaranteed but are they typically MOT friendly? Also don't want any more volume; it's loud enough as it is.

If you have stock secondary cat you will fly MOT, even with a decatted manifold, so no worries there.

You will get more noise going to a decat manifold, but in my experience the increase in noise is far less than that from the catback. If you have the money to change manifold before remap, it's 100% worth doing. I didn't, and after the remap was disappointed with how much worse the torque dip was (it improved with the remap, but because everywhere else was better, the torque dip became a real source of disappointment).

[BenGt86 0]

Anyone have problems with passing MOT and noise ? Just about to fit my agency power cat back 👍

[Lauren 2259]

If you keep the primary cat, you will pass emissions no problem. You can just about get away with it, with the second cat only as well. 

As for noise, not an issue, unless you have a stupidly loud exhaust. YMMV of course. 

[Willtl 54]

Looking for some opinions here. Had the Milltek non resonated fitted in August but returned to stock the following week as it caused "head problems". Due to lack of selling success, I'm thinking of getting it refitted but replacing the centre pipe with the resonated version. I did like the sound of start up and idling, but my poor head just can't live with the droning. So my question is, if I switch to the resonated version am I likely to end up with the nice starting and idling tunes, but no droning? Ideally I'd like the motorway runs to be close to stock so I don't throw away a few hundred on putting the Milltek back on and then returning to stock.....

As people mention the exhausts quieten down over time, can anyone offer an approximate mileage by when I could expect this?

Thanks!

[Lauren 2259]

That's interesting as I've run a non-Res Milltek from the point of delivery for my car for the last 90K miles. 80 of those have been with a decat and overpipe. There's no droning on a constant throttle and I've taken over the continent four times now. So I'm really surprised you feel that it drones. I think maybe you should have given it longer? On cruise control for example you don't hear it at all really. It's only when you accelerate that you will hear it a little. 

I'm not convinced exhausts quieten really after time. It may be hard to tell though as I'm on my 4th Milltek! But had the current one on for 20K miles or so. It's a fair bit quiter with the extra silencer, so maybe that is a way forward for you? 

[rob275 1817]

If you had it fitted in August it should have carboned up by now as it only takes a few hundred. Should be quieter but i'm with Lauren it doesn't drone particularly, the resonated pipe will of course fix it though.

[Foulsmell 120]

I've got the resonated version. No real drone on the motorway and it's neighbour friendly etc. I've got a higher final drive too and still good for the MW.

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[Willtl 54]

Thanks for the comments. All the other parts were stock, with the exception of a HFC (which has also been returned to stock). I've read various opinions on this, but does anyone know for sure whether the HFC could be contributing much to the droning? (I say droning, but it may just be overall noise the exhaust system could be creating that is playing havoc with my head). If opinions are that the HFC could be contributing and the exhaust will quieten down after a few hundred miles (it was on 180 at time of removal), maybe I'll just get the non resonated put back on without the HFC and see if I can put up with it for a few hundred miles to see if it really does quieten down to acceptable levels.

 

Lauren - why are you getting through so many exhausts? Is it down to your particular usage or that Milltek exhausts only have a limited life? I had my Alfa 156 from new for 13 years and 80,000 miles, all on the original exhaust!

[Willtl 54]

23 minutes ago, Foulsmell said:

I've got the resonated version. No real drone on the motorway and it's neighbour friendly etc. I've got a higher final drive too and still good for the MW.

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Does it still have a nice sound on start up and idle?

[Ade 517]

2 minutes ago, Willtl said:

Does it still have a nice sound on start up and idle?

If you can wait a few months, I'm getting a custom cat back made.

70mm piping and 3 massive silencers with halmholtz resonators. It should be very very quiet on an N/A car. Will post something when its completed.