Exhaust valve replacement - Mod Stock review

[paddy1000111]

Hi all,

I have a 2016 v6s and my exhaust valves suffered the usual failure. Had it checked by the independent whilst it was in for other work and they confirmed the issue as irreparable.

I did some googling and came across mod_stock on the forum but didn't find any specific review.

There are a few options to choose from, prices are as of 03-02-24 so may change:

1) Exchange the box via post. They offer an exchange service where they send you down a repaired box where they have cut out the failed valves and replaced them with uprated valves with stronger springs that come with an ownership warranty (as long as you own the vehilce) the cost for this was £360 plus postage both ways plus a £350 refundable deposit given back when your old unit is returned.

2) They will come and replace it in person. This is the option I chose as by the time I paid for postage and the local independent to replace it, it was more expensive to have the exchange unit. They drove down and replaced it for me for the price of £420 (360 + 60 fitting). They put the car up on ramps and it took roughly 30 mins.

3) you can purchase the valves from their website and have a local exhaust company do the work for you. They are £120 each and then it's down to how much your local repair shop charges for the repair. I'm not sure about warranty with this repair.

4) The mod. This is the same as the first two services but they cut the oem box open and make the loud side louder. I love the idea but I already worry about waking the neighbours with my morning bark so I opted against it. The cost for this is £720 plus postage or plus the fitting fee.

I couldn't be happier with the service I received. They took around 30 minutes to do my exhaust, I met them in a car park in the area that they were working in that day as I wanted it done ASAP and didn't want to wait for them to come to my area. Whilst they were under the car they also looked around and pointed out some bits I may need to sort in the future which I really appreciate as it wasn't part of the service they offer.

They also offer remapping services and are in the process of getting set up for gearbox remapping for the ftype too.

Overall a very happy customer and can't recommend them enough if you have the exhaust issues I did

 

[cj10jeeper]

Always nice to see posts where a solution is both showed in a good write up, costs and experience of it.
Overall sounds like a really good idea and service

Just a comment regarding the back box. Since it's exchanged for a prior customers then you really don't have any idea what box is being fitted. For example my back box was replaced under warranty shortly after I purchased the car, so am on a 2018/19 box on a 2013 car. I'd not be happy to swap a 5/6 year old box for say a 2013 that's many years older, more corroded, etc.
Of course you might be lucky and get a much newer and better condition box.

 

[Moss]

Where are they based?
The website of theirs doesn’t seem to mention location….

 

[Webarno]

Funnily enough, I visited them yesterday at their site in Epsom and had the new valves and mod done.

My old valves hadn’t failed completely, but they did emit an awful loud squeak every time they opened and closed which was very annoying and a little embarrassing.

Now, no more squeaks and the car is still nice and quiet with the valves closed which is what I wanted.
With them open though, my god, it’s a violent beast.
It was nice and loud before, but now, it’s a little louder but the tone is slightly more aggressive, with more pops.

I’m extremely happy and wouldn’t hesitate to recommend them, even just for the valve replacement alone.

 

[paddy1000111]

Always nice to see posts where a solution is both showed in a good write up, costs and experience of it.
Overall sounds like a really good idea and service

Just a comment regarding the back box. Since it's exchanged for a prior customers then you really don't have any idea what box is being fitted. For example my back box was replaced under warranty shortly after I purchased the car, so am on a 2018/19 box on a 2013 car. I'd not be happy to swap a 5/6 year old box for say a 2013 that's many years older, more corroded, etc.
Of course you might be lucky and get a much newer and better condition box.

I get where you're coming from. I would say though that the box I had fitted was clean and had no corrosion, the tips were clean and polished and there was no damage to be seen. I suppose it's down to cost, you could get a replacement box from jaguar with the dodgy factory valves that will last an unknown amount of time for a hefty fee (outside of warranty) or you pay £360+ fitting for a backbox with sturdier valves and a lifetime of ownership warranty. I suppose if you have a warranty that covers the exhaust (mine doesn't) you would be silly to not get a new exhaust for free from jag and then if the valves fail you could always send it to them for the replacement valves and have the same box back if you wanted, or buy the valves and have a local company retrofit them.

The box that came off my car (2016) was pretty spotless but they did note that some muppet had tried to remove it in the past and lightly dented the pipework, apparently they have a pipe former that would re-shape them so not a real issue. As far as I'm aware the back boxes on these are stainless so corrosion shouldnt really be an issue as its corrosion resistant. They did inspect my box at removal anyway and said that if they took it off and the physical box was destroyed then I would have to pay for them to source another box which was apparently quite cheap due to the amount of failed valve boxes they come accross.

They were a genuine pair of guys and I considering the attention to detail with the new exhaust and the fitting process like lubricating the T30 screws on the little bit of trim as they corrode in. I can't imagine them sending out old rusty boxes with some new valves on.

 

[paddy1000111]

Where are they based?
The website of theirs doesn’t seem to mention location….

Epsom I believe. They travel all over the UK though so if you want them to do it you may have to wait for them to be in your area as they do a load of vehicles in a day hence why the price is low for fitting

Apparently their facilities are good though, they even have full motion racing sims to keep you entertained whilst you wait

 

[KN05]

Had mine done by them in Hartlepool last week, it sounds even better now!

 

[Tom Sawyer]

Had my back box done by them last week, good guys working long days.

They called to my place in North Derbyshire on route to the NE, unfortunately I haven’t had a proper chance to use it yet, but am glad to read the previous positive comments as my initial thoughts were of slight disappointment.

 

[Andrew24]

Thanks for the info, worth remembering.

 

[ToyCarMan]

This is great info, and I am now (unfortunately) in a similar situation with one of my exhaust valves having seized closed.

At first I thought it might have been an issue with the vacuum pump or air hose however having gotten the wife to rev the engine while its on ramps with me underneath (scary times) I can see that the other value works fine (if a bit squeeky).

My Attempts
Got some PlusGas and with the help of a small hammer and screwdriver I managed to back and forth persude the valve to moving again by hand but it wont respond under air pressure or return back to a resting position like the other valve does - so I think the internal spring is either faulty/rusty/clogged etc.

I think Mod-Stock might be my only option:
https://mod-stock.co.uk/collections...8-replacement-exhaust-valve-sold-individually

Questions:

• Are the oem valves removable without cutting or do they have to be welded into the gap when the oem ones are removed?

• Are the air hoses easy to pull off the valves? - If so, this could be a summer job as I might be able to remove the Catback myself.

• Typically - I live no where near Mod-Stock so it would have to be me or a local garage that does the work. Has anyone gotten their local garage to fit these valves? - If so was it a pain/expensive?

• I can't figure out the Mod-Stock pic. It shows a valve with 2 butterfly fins. Do you think this is just two seperate valves photogrphed together with one being behind the other? :

If anyone can recommend a dependable Jag garage in Scotland (central belt preferable) then that would be great as I have a few other projects I would like to pursue after this is resolved.

Thanks in advance.

 

[iamandyf96]

This is great info, and I am now (unfortunately) in a similar situation with one of my exhaust valves having seized closed.

At first I thought it might have been an issue with the vacuum pump or air hose however having gotten the wife to rev the engine while its on ramps with me underneath (scary times) I can see that the other value works fine (if a bit squeeky).

My Attempts
Got some PlusGas and with the help of a small hammer and screwdriver I managed to back and forth persude the valve to moving again by hand but it wont respond under air pressure or return back to a resting position like the other valve does - so I think the internal spring is either faulty/rusty/clogged etc.

I think Mod-Stock might be my only option:
https://mod-stock.co.uk/collections...8-replacement-exhaust-valve-sold-individually

Questions:

• Are the oem valves removable without cutting or do they have to be welded into the gap when the oem ones are removed?

• Are the air hoses easy to pull off the valves? - If so, this could be a summer job as I might be able to remove the Catback myself.

• Typically - I live no where near Mod-Stock so it would have to be me or a local garage that does the work. Has anyone gotten their local garage to fit these valves? - If so was it a pain/expensive?

• I can't figure out the Mod-Stock pic. It shows a valve with 2 butterfly fins. Do you think this is just two seperate valves photogrphed together with one being behind the other? :

If anyone can recommend a dependable Jag garage in Scotland (central belt preferable) then that would be great as I have a few other projects I would like to pursue after this is resolved.

Thanks in advance.

1. No, you need to cut the valves out and re-weld the new ones back in place. They are attached to the backbox so you can take it off the car and weld it relatively easily without having to weld on the car.
2. Yeah it's pretty easy to take it off.
3. Modstock will come up to Scotland to fit it. If you message them and tell them you are wanting their backbox, they will come up here once they have enough people wanting and get them all done in one visit. I asked them in Feb and they said they'd be up once they get enough interest. Messaged again in April and they said they will be up soon becuase they have had enough requests to make it financially viable to make the trip. If you want it, might be worth asking ASAP to get your name on the list when they do come up.
4. That picture is 2 valves sitting on top of each other.

 

[gf15]

Thank you all for the info. Really appreciated.
For noise levels, we did a little tour with a Lotus Emira, a TVR Chimaera 450 and my v6s. We swapped cars, so had the chance to see and hear the Jag noise from behind. I still am on the original exhaust, but it was loud when it was being driven hard. Easily the loudest of the 3.

Jag was really liked by my mates.

All 3 cars were different, but fantastic drivers cars.

 

[ToyCarMan]

This is great info, and I am now (unfortunately) in a similar situation with one of my exhaust valves having seized closed.

If anyone can recommend a dependable Jag garage in Scotland (central belt preferable) then that would be great as I have a few other projects I would like to pursue after this is resolved.

Thanks in advance.

1. No, you need to cut the valves out and re-weld the new ones back in place. They are attached to the backbox so you can take it off the car and weld it relatively easily without having to weld on the car.
2. Yeah it's pretty easy to take it off.
3. Modstock will come up to Scotland to fit it. If you message them and tell them you are wanting their backbox, they will come up here once they have enough people wanting and get them all done in one visit. I asked them in Feb and they said they'd be up once they get enough interest. Messaged again in April and they said they will be up soon becuase they have had enough requests to make it financially viable to make the trip. If you want it, might be worth asking ASAP to get your name on the list when they do come up.
4. That picture is 2 valves sitting on top of each other.

Thanks - I contacted Mod Stock about the replacement fitting and my name is on the list - they suggeted Sept/Oct for a Scotland visit.

Hope its a weekend

 

[Andyp123]

Just had my valves replaced lovely guys top job would highly recommend them.

 

[Geetee68]

Another thumbs up for Mod-Stock. I was happy with the noise on mine but the valves rattling and scraping was doing my head in. Mod-Stock came yesterday to my home, removed the box, cut out the old valves, welded the new valves, and re-fitted so I retained my own box. Sounds sweet now. Excellent guys and great knowledge. They did say they are also investigating a fix for the known DLR issues so I’ll keep an eye on that