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Just fitted my GRP decat, perfect fit, though i recommend this harbor freight pipe expander to use on the existing exhaust - https://www.harborfreight.com/automotive-motorcycle/exhaust/large-tail-pipe-expander-63704.html Best $19 you'll spend.

After installation delighted with the sound & throttle blips on downshift are definitely cleaner.

btw Guy came up to me on the Ferry & asked if the car was as good as it sounds!
Thanks for the tip on the pipe expander! That seems to solve the bigger challenge of this install! And yes, the car it definitely as good as it sounds! Is it the ferry on the Long Island Sounds?
 

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Spent about 3 hours last night installing the GRP decat pipe and it was successful!! Got a chance to dive the car this morning and the sound is amazing!!! I used the exhaust pipe expander tool and the new pipe went in pretty easy. However, it was a tiny bit too long and I had to cut it to fit...Every exhaust is probably a little different.

If you are working by yourself, find something to support the muffler. It gets heavy after a while. I used a spare rim laying around the garage. :grin2:
 

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Just installed the grp decat pipe today... holy hell this thing screams now! Significantly louder under normal driving circumstances and absolutely ridiculous above 4000 at WOT!

Went over to my buddies house and we knocked it out in a little under an hour. Super simple to do. Basically just remove the bolts holding the rear end cover shield. Undo the clamp that connects the exhaust assembly to the Y pipe. Take off the four screws holding the exhaust assembly in place and it easily comes out to finish the job. Undo the last clamp on the pipe to remove it. We had to beat it pretty good with a rubber mallet to get it to come off. Just working the cat pipe around a bunch to get it to free up to pull out. We picked up a rental pipe expander which you will definitely want to make things go easy. Use it to Open up the pipe where you insert the new pipe into. And simply re-install the exhaust assembly in place and bolt on the new Decat pipe. slap the cover back on and you are all set to piss off your neighbors!

Wasn’t sure what to expect with the sound and throttle response, but after done I am extremely impressed!

Few pics





 

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I didn't find the need to use an expander or much of anything really other than some time with the mallet to disgorge the 3rd cat... and then some graphite spray to install the GRP unit. That said, man this stock exhaust is heavy though....!!! At least the weight is low. One of my best friends is a master tech for Maserati and had harsh words on my OSHA compliance, however. :D
 

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I didn't find the need to use an expander or much of anything really other than some time with the mallet to disgorge the 3rd cat... and then some graphite spray to install the GRP unit. That said, man this stock exhaust is heavy though....!!! At least the weight is low. One of my best friends is a master tech for Maserati and had harsh words on my OSHA compliance, however. :D


I had the same experience. My 3rd cat was Incredibly difficult to remove from the muffler. I bet it took 30 min of working it back and forth and prying on it. And the new one slipped right in after, no problem.

I also found that the bend radius was slightly different than the original cat. When I first went to install it, it was about 1/2” off from meeting up to the old pipe on the engine side. I had to leave everything very loosely connected to get things together, then gradually tighten it all up.

Sounds amazing:)


Sent from my iPhone using Tapatalk
 

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... Also I lifted up the stock exhaust and Larini exhaust and the Larini was much lighter, i would say felt like half the weight. So at only like $1,500 it's a bargain to change for the weight savings along with a much improved sound. For my R8's and Huracan exhaust changes were $6k-$7k. Again thanks for the help on this Greg.
The Evora How-to section has a thread on weights with a link to google spreadsheet. While these are Series 1 exhausts not the 3" 4xx series I cannot imagine the OEM being any lighter while the Larini's take a BIG chuck of weight out.

I have just hear across the channel that Lotus is now offering a non-valved sport exhaust that's quieter than stock to be able to meet the harsh track sound level limitations, the unit weights about 3 kg less than OEM.
 

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Just installed GRP's decat pipe today. As others have said, the pipe expander tool helps, not to mention dropping the whole muffler is the way to go. I tried for awhile to just slide it in to no avail. Ultimately the way I got the correct alignment was to drop the muffler, attach the decat pipe loosely to the v-band clamp, then slide the decat and muffler into place. Lastly tighten everything up.

The sound below 3k rpm is largely similar to stock, but above 4k rpm the shriek is much more raw as well as noticeably louder.
I made a quick comparison video of the sound between stock catted exhaust and with the GRP decat.
 

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I ordered a GRP decat pipe earlier this week. They were out of stock, but in production with availability estimated for next week. A couple days later I got an email stating that the pipe was being shipped out. It was delivered by USPS during lunch today and it is now installed and terrorizing the neighbors. Exceptional customer service from Greg and a nicely made part. I now see why everyone is so pleased with this easy mod.
 

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Maniacal Motorist
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Evora S Decat

There don’t seem to be any US suppliers of an Evora S decat pipe? I decided to take my unit with secondary cat to have it duplicated, sans cat, for $90. I recall that a few members had decat pipes custom-fabbed.
 

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I finally had this done and wanted to post a thank you to the OP for this idea/suggestion.

In fact, I saw this thread 6+ months ago and sent it to GRP asking if they would make a plug-n-play decat pipe for the 400s. Thanks to GRP for taking up the suggestion and making this available.

I agree with the OP that this makes an instantly noticeable positive difference. It increases loudness, changes tone to a much deeper and hard hitting tone, and lowers the wail about 1000 rpms or so - i.e., the better sounding higher tones now starts at 2200-2300 rpms instead of over 3500 rpms before the decat (I'm a 6 speed manual, not sure if gear ratios for IPS are different).

I had my local Lotus race shop (Sports Car World in Dallas) install Greg's pipe and they are a pleasure to work with @DerekOfBass. But as others in this thread have posted, it seems doable at home with hand tools. Definitely get the pipe expander from Amazon!

400 owners, definitely do this! Very worthwhile mod.
 

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Now you need GRP cold air intake. Since adding that I can't get enough of driving this car and the lambo has spent more time parked in garage
How hard is the intake install? I heard getting the stock airbox out is quite difficult.
 

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OK I wanted to add after having driven a few miles after 3rd cat delete - throttle response has improved as well. I thought so yesterday after picking car up but wanted to make sure before I posted it. Definitely feels more eager to spool up now.
 

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How hard is the intake install? I heard getting the stock airbox out is quite difficult.
I had heard that also so I let dealership do the install as they had just down one on my friends car. It only took less than an hour so must not have been that bad. One thing the tech found when he did both installs was to trim the hose a bit and that made installing new one easier
 

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I didn't find the need to use an expander or much of anything really other than some time with the mallet to disgorge the 3rd cat... and then some graphite spray to install the GRP unit. That said, man this stock exhaust is heavy though....!!! At least the weight is low. One of my best friends is a master tech for Maserati and had harsh words on my OSHA compliance, however. :D
Hydraulics shouldn't be used to hold weight. If you crawl under that, you're one failing seal away from being crushed.
 

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I ordered a GRP decat pipe earlier this week. They were out of stock, but in production with availability estimated for next week. A couple days later I got an email stating that the pipe was being shipped out. It was delivered by USPS during lunch today and it is now installed and terrorizing the neighbors. Exceptional customer service from Greg and a nicely made part. I now see why everyone is so pleased with this easy mod.
I got the same response from Greg late last week when I ordered mine. I was expecting at least a week or two of delay but to my surprise I got a confirmation of shipment just a couple of days later. Mine should arrive today!

Ya'll say I don't have to lift the car to get 'er done. That would be good because I don't think my car will fit on my bike lift :))) and I don't have any way to support the car except on its own wheels.
 
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