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2021 Evora GT, Monoco White, 6sp, black+red interior, glass hatch
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Discussion Starter · #1 ·
REMOVAL OF THE LOTUS EVORA GT 3RD CATALYTIC CONVERTER

This photo only, not my photo or car.
Motor vehicle Automotive exterior Automotive design Auto part Metal


After removing the four bolts that hold the muffler retaining bars on, I had my wife help assist me in removing the muffler. It helps to have visuals in front of and behind the stabilizing bar. Super easy. My 2021 Evora GT’s band clamp is spot welded and therefore not removable and can only be opened in place. There is no need to remove the perforated panel.

Tools needed for muffler removal:
4mm - Allen wrench, 4 rearmost to perforated panel
5mm - Allen wrench, 2 at front corners of panel
10mm - 4 bolts that hold the muffler, 5 bolts at front panel edge
11mm - “V” clamp on muffler pipe
15mm, 5/8”, deep well - muffler band clamp

Hood Light Automotive tire Black Grille


After watching a half-dozen videos, I thought removing the cat was going to be a struggle. After prep, it took me about three minutes (of tapping) to get it off. I positioned the muffler assembly so that when I sprayed the Fluid Film (lanolin based, non-volatile) it would gravity assist moving between the parts. I waited. I would then twist it back-and-forth about 90°. I repeated this three times over approximately 15 minutes. I positioned the muffler on the carpet (scrap in my shop) and twisted the catalytic converter up, so it was vertical. I put the flat surface of the rubber mount against the front of my ankle so the muffler wouldn’t move when I hit the converter (I was facing toward the bottom of the photo.). Then I used the 4lb. dead blow hammer to, as gently as I could, knock it off. I didn’t want to damage the catalytic converter figuring that maybe the honeycomb and other bits in there are a bit delicate.

Automotive exhaust Household hardware Muffler Cylinder Gas


These photos show the issue this product from GRP/GregsRaceParts has. It’s easily apparent the bend of the OEM piece is more acute. Note how the inner curve of the OEM’s elbow has a much shorter radius. This results in less straight pipe at its downstream end and its inability to be inserted fully. Insertion is not hampered by the downstream pipe's inner diameter, only by the curve. Increasing the inner diameter will only result in leakage. The small Sharpie mark on the decat (2nd photo below) is the insertable distance of the OEM part. Note that it is well into the curve of the pipe.

Automotive exhaust Bicycle part Gas Auto part Nickel


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If you visualize the distance between the Sharpie mark and the scratches (above photo) you will understand the misalignment in the picture below. I needed a trigger operated clamp (with rubber working surfaces) in order to place the V clamp. I hope the flex pipe (upstream) can accommodate that much deformation over time.

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The flex pipe.

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Decat installed:

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Good write up. People seem to get caught up on this by trying to remove the cat with the muffler in situ. Myself included. Removing the whole shebang makes it a quick job.

Careful that Lotus doesn’t hunt you down and revoke your powertrain warranty!!

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2017 Evora 400
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What was the point of your thread? Was it:

1) A how to? In which case it would have been better placed in the How To Section, there's already a good thread with a how-to included here

or

2) The Cat pipe doesn't fit very well? Have you talked with GRP?

It may be an optical illusion, but in your picture (below) it doesn't appear that the bend goes through 90 degrees?:
picture
 

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I think he was "Calling Occupants from Interplanetary Craft"
 

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2021 Evora GT, Monoco White, 6sp, black+red interior, glass hatch
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Discussion Starter · #6 ·
What was the point of your thread? Was it:

1) A how to? In which case it would have been better placed in the How To Section, there's already a good thread with a how-to included here

or

2) The Cat pipe doesn't fit very well? Have you talked with GRP?

It may be an optical illusion, but in your picture (below) it doesn't appear that the bend goes through 90 degrees?:
picture
Yes,. I did discuss this with GRP.
 

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2021 Evora GT, Monoco White, 6sp, black+red interior, glass hatch
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Discussion Starter · #7 ·
Yes,. I did discuss this with GRP.
Sorry, new to the site.I should have checked more broadly (under 400 & 410 also). I only saw posts under GT. I was unaware of 'How To'.
 

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Not having proper tools and a work space I took my GT to my local shop a week or so ago for the decat install. As stated the bend on the decat makes fitting not as smooth as it should be. If the bend was slightly sharper, closer to a 90 degree bend install would be so much easier and fitment to OEM exhaust would be better.

my shop was about to give up and state it doesn’t fit…. Mostly due to when fitted he felt it’s kinda binding the exhaust.

it does look like the latest decat has a sharper bend…. I purchased my pipe on Black Friday 2021.
 

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Discussion Starter · #11 ·

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I didn't have this problem when I installed mine but it's been on for a couple of years so it was not made recently. The only annoyance I experienced was getting the cat off the pipe.

I'm not sure it would legally void the warranty. It certainly shouldn't but in the event of concern it's easy enough to switch back to all three cats. The car never notices it either way except that it sounds better.
 

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2017 Evora 400
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Not having proper tools and a work space I took my GT to my local shop a week or so ago for the decat install. As stated the bend on the decat makes fitting not as smooth as it should be. If the bend was slightly sharper, closer to a 90 degree bend install would be so much easier and fitment to OEM exhaust would be better.

my shop was about to give up and state it doesn’t fit…. Mostly due to when fitted he felt it’s kinda binding the exhaust.

it does look like the latest decat has a sharper bend…. I purchased my pipe on Black Friday 2021.
I bought one from the same batch and it was a pain to install. I was able to pull it together with the v band clamp but it took some muscle to align.
 

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2021 Evora GT, Monoco White, 6sp, black+red interior, glass hatch
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Discussion Starter · #15 ·
I bought one from the same batch and it was a pain to install. I was able to pull it together with the v band clamp but it took some muscle to align.
I feel (have felt?) your pain!
 

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Discussion Starter · #16 ·
Here’s an idea for those that might like to fabricate their own decat pipe for about $85 before tax. One that has a small radius at its bend.The drawing has the measurements of the blank in pink and those of the OEM cat in black. You can see, this 3’ SS pipe should be long enough.
Rectangle Parallel Font Gas Drawing


Vibrant (13042) 90° T304 Stainless Steel Mandrel Bend Tube
The blank:

You'll need a V-band flange on the upstream end. You only need one of the flanges. I’m assuming that V-band flange shapes are standardized.
SYKRSS 3.0" Universal Stainless Steel V Band Clamp Flat Flange Kit Assembly
The flange Kit:


Now all most of you need is a metal shop. Some could just fire up their band saw and TIG welder.
 
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