3rd Cat Delete on Emira – Is the Milltek Valve Controller Really Necessary?

[samjoshua]

Hey everyone,

I'm planning to install the 3rd cat delete on my Lotus Emira soon. However, I’ve been wondering whether it's actually necessary to also install the Milltek valve controller.

From what I understand, when you’re in Track mode, the exhaust valves are already fully open (100%). So, is there any real benefit to adding the valve controller if I mostly drive in Track mode anyway?

Would love to hear your thoughts and experiences—thanks in advance!

 

[F1 SML8R]

It's never 100% open at idle/startup in any mode. However, in sport and track modes it does go from partially open at start-up to fully open at a predefined rpm threshold. I personally, like the OE functionality. With that said, the partial opening in sport and track modes under the RPM threshold that is defined just seems silly.

 

[jjslat]

Save yourself the time and money and do it all at once. I had the same thought you did and did 3rd cat first. Low RPM's and when parked it's still valves closed in any mode, I know idle is partially open but as soon as you touch the throttle it closes. I programmed valves open button and OEM mode to my mirrors homelink button which works great and gives OEM feel. I only use OEM touring mode when I'm leaving early or coming in late, sounds awesome otherwise with valves open all the time.
I waited about a week to order the Milltek valve controller. I did call Greg first and he made a good argument that the cheaper V1 controller is just fine and probably easier to install.

 

[Vampyre]

Did both at the same time and well worth it, save's time. I like the sound with the valve always open.

 

[F1 SML8R]

...I know idle is partially open but as soon as you touch the throttle it closes.

I don't believe this is accurate.

There's a sticky somewhere that explains all of the driver modes with all the specifics. However, one of the specifics is that in sport or track, it partially opens when these modes are initiated(I believe about a 1/3 open). From there, it only remains at this partially open state then opens fully after a certain RPM threshold, ultimately dropping back to the partially open state when it falls under the RPM threshold.

 

[jjslat]

I don't believe this is accurate.

There's a sticky somewhere that explains all of the driver modes with all the specifics. However, one of the specifics is that in sport or track, it partially opens when these modes are initiated(I believe about a 1/3 open). From there, it only remains at this partially open state then opens fully after a certain RPM threshold, ultimately dropping back to the partially open state when it falls under the RPM threshold.

You're probably right, all I mean is unmodified in track mode idle sounds decent but if you try to rev the engine while stopped it sounds like the valve is closed. With the valve controller it's for sure a little louder at idle and much louder when revving at a stop

 

[Dragoon]

IMO it's best to do both, and it's easy to install the controller while you're in there installing the cat delete.

 

[KAR120C]

I did not install a valve controller and just let the OE software do it's thing.

First - 3rd cat delete sounds fantastic. Much better sound. I nearly always change my car exhausts, but Emira stock exhaust without 3rd cat sounds just right to me.

In my opinion

CON:
Yes, you have to change the mode to Sport or Track on startup, which takes 2 seconds and is just part of my startup routine

PROS:
-No additional stuff needed.
-Idle is definitely louder in Sport and Track.
-No chance of leaving it in closed mode under hard throttle which can damage the engine. Even in stock non-open mode, the software will open the valve under hard loads or high rpms to protect the engine from too much backpressure.

Not sure why a secondary valve controller is necessary when the stock controller works seamlessly with the drive mode.

 

[seriously]

The main benefit of the controller is being able to go full open from idle. Both sport and track modes go from partial open to full open at different points and have more aggressive off throttle sound. It’s fantastic on full tilt. I personally am very happy with the OEM function. If you must have full open at idle the value controller is the way to go.

 

[samjoshua]

Thanks a lot for your quick replies on this topic!

I think I’ll go with the valve controller, as I really like having the exhaust fully open at idle. Worst case, I can always switch it back to OEM mode using the controller.

As for startup without a valve controller, it’s possible to hold the start/stop button for about 10 seconds to turn on the ignition (without starting the engine), then activate Track mode while the engine is still off — that way, you get a loud startup!

 

[idleuser]

Your second option is to just install the 3rd cat first, turn on the car and toggle the sport / track setting to see if the valve controller is even needed.

Personally, I'm satisfied with just the 3rd cat delete.

 

[allenyao09]

I did the VC first and then 3rd cat delete. I think the VC had a much more noticeable difference. Even in sport or track mode you would not get 100% open until high revs.

 

[sbproducer]

I'm in the 3rd cat delete without valve controller camp. Just don't want to deal with the hassle of potential problems and don't really need the loud startup and louder sound at low rpm. Car gets way too much attention as is... Sounds great when driving hard.

 

[Rupes]

I went with the 3rd cat delete and no valve controller. I'm happy with the sound, especially above 4k RPM where it howls, but sometimes I wish I had additional control over the sound at a lower RPM.

It seemed that many of the Milltek early adopters had problems with the valve controllers melting and occasional CEL's. This all seems pretty well sorted now, and the placement of the controller definitely matters, but I still see some folks are dealing with melting months later under high temperature/track use.

I think the stock software does a pretty good job of managing the flaps, and I didn't want to mess with this too much if it had some (small) potential of disrupting the car. I wouldn't blame you for feeling differently, and I think the risk is pretty low if you go with the controller. Either way, the removal of the cat is worth it, so no hesitation there.

 

[samjoshua]

I understand the idea of not messing with the electronics and avoiding any potential issues — and I like staying as oem as possible.

Does anyone have a video of revs or exhaust sound with just the 3rd cat delete and no valve controller? Would be great to compare!

 

[FearGuise]

I understand the idea of not messing with the electronics and avoiding any potential issues — and I like staying as oem as possible.

Does anyone have a video of revs or exhaust sound with just the 3rd cat delete and no valve controller? Would be great to compare!

 

[samjoshua]

Thanks for the video!

Do you think that if I do the cat delete and the valve controller, it might be annoying when cruising on the highway with the valves closed?

 

[chirowolf]

For me doing both at the same time was great. I love being able control the sound at will. Easy install with relatively minimal price

 

[shinoo]

Thanks for the video!

Do you think that if I do the cat delete and the valve controller, it might be annoying when cruising on the highway with the valves closed?

No, I cruised on the highway for hours testing both open and closed. No problem. Our Emira Decat pipe now comes with a gasket and hardware so bolts on easily.

 

[MAX FPS]

Related question: does anyone know if the vehicle can still pass a state smog check with the 3rd cat deleted? It seems a popular option, and I'm not sure if the 3rd cat was only needed for EU emissions? If it can't pass, what is your plan when a smog check becomes necessary to renew registration?