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

[SX 10TUS]

I think if you want it loud at idle/low revs, you will need the valve controller.

If you want it to scream and howl above 4k RPM, pair the 3rd cat delete with the GRP blue dry air filter, and possibly release a couple of horses too...

The 3rd cat delete on its own won't make too much difference and will be quite subtle...

Also remember the louder the exhaust the less supercharger whine you will hear...

 

[samjoshua]

Alright, I’m definitely leaning towards the valve controller and the 3rd cat delete.
Would you go for the Komo-Tec valve controller for the Milltek v2 setup?
Since they’re the same price, which one works better ?

 

[BobbyG]

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?

It’s my understanding that the 3rd cat is not monitored, so the cat delete shouldn’t cause an issue (at least where
I live). I’m sure more knowledgeable members will chime in as well.

I have the Milltek exhaust, 3rd cat delete, and valve controller. Absolutely love it..

Also added GRP cold air intake, GRP V2 short shift kit, GRP wheel spacers, GRP lowering kit, and the JB4. Picking up the car today from the installation shop.

 

[B r I a n]

Short answer: No

 

[brainf18]

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!

I did the third cat delete and did not bother with the valve controller. Happy with the choice and don't feel like I'm missing anything....and as a bonus its one less thing to purchase and install.

 

[Steve24]

I’m not interested in doing it.
Do the 3rd cat delete, for sure.

Controller? WOFTAM as far as I’m concerned.
It’s all about noise. There’s no other benefit.
And several other hassles come with it.

That said, if it’s noise you want, go for it.

 

[BobbyG]

I enjoy the exhaust note with the valves open all the time when I’m driving solo. With the wife as copilot, I go back to the OEM setup.

To each their own

Noise to me is a Honda Civic with some ridiculous aftermarket straight pipe or similar muffler set up.

 

[shinoo]

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?

Yes, as this third cat is post the O2 sensors. Technically you are messing with the emissions equipment which is not legal. I would be surprised if any inspection includes taking the rear of the car apart to inspect.

FYI, these third cats are installed to add longevity to the emissions performance. When the primary cats begin to lose performance, this third cat can play clean-up...I believe it may have been prompted by CARB.

 

[sixtyy]

I think if you want it loud at idle/low revs, you will need the valve controller.

If you want it to scream and howl above 4k RPM, pair the 3rd cat delete with the GRP blue dry air filter, and possibly release a couple of horses too...

The 3rd cat delete on its own won't make too much difference and will be quite subtle...

Also remember the louder the exhaust the less supercharger whine you will hear...

GRP cold air intake should make supercharger sound more prominent.

 

[ManOfSteel]

I opted to just delete the 3rd cat in May. I'm VERY happy with the result. Goldilocks says "just right".

 

[Dragoon]

If you want to reduce drone and enjoy a quieter cabin, consider swapping the factory exhaust tips for tips that are a solid-pipe. The factory exhaust tips are perforated with numerous holes and vents, which cause a significant amount of drone. Switching my exhaust tips to solid titanium ones from GRP with my titanium exhaust drastically reduced the cabin's exhaust sound. Now the exhaust noise fires directly out the back of the car instead of getting trapped under the car and in the bumper. Sometimes I've had to roll my windows down to enjoy my cat delete, valve open, titanium exhaust. Otherwise, it's hard to tell how awesome it sounds outside with the windows up.

 

[Tracked Emira]

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.

Heat wrap the harness or you’ll be sorry.
Get Version 2 even if it’s a little more.
If they made a version 2 there’s a good reason for it.

 

[FlyNavy01]

I'm apparently the opposite of most here and would have preferred I had saved the time and money on removing the 3rd cat since it didn't change much, maybe 10-20% louder to my ears. I also don't really enjoy the increased pops and burbles that come with it removed as I feel that's more fitting of cheaper boy racer type cars.

The valve controller made a much bigger difference (maybe 30-40% louder and deeper tone from idle) and it can be installed in 15 minutes. Added bonus of keeping the 3rd cat is less emissions because I'm a loser who likes cleaner air ha, I'm just too lazy to swap it back to stock for now.