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I'll be happy to weigh my sport cats with blankets for you. I can't imagine much of a difference between original cats and sports cats with blankets. Your biggest savings will be cats to catless.
Hi FoeH, I realize your post is just under a year, but i think it's still relevant) Did your 2M Perf Cats come with the donut (tapered gasket) for the driver side? Parts that came with mine were two O2 spacer, 1 pair of ~paper gaskets for headers2cats, 4 three inch springs (for heat blankets), two bags of nuts, washers, two crush washers, and three sized bolts. I'm thinking they forgot the donut gasket and the right rear gasket (to the exhaust). If they didn't come with your order, where did you order the donut and the other gasket? Thanks.
I'll leave my review here as well. I'm not finished installing my 2M cat deletes yet but here's what I have so far that may help some people wanting to buy these:
1.) When you order cat deletes without gaskets through 2M, be prepared to need to buy 2 gaskets yourself from GM. The stock cats have 4 gaskets total, 2 O-style gaskets that sit recessed in the manifold side of the cat, one donut style gasket on the driver's side cat on the cat back side, and one triangle gasket on the passenger's side on the cat back side. The 2M cat delete pipes do NOT have recesses in the pipes on the manifold side for the stock O-style gaskets to fit into. You will need to either buy 2M's triangle gaskets with your delete pipes which they charge an extra $70 for, or you can buy separately through a GM dealer for $24 (part number is 23194206 you'll need 2 - they are $12 each). These 2 triangle gaskets will go on the manifold side of the cat delete pipes. You will reuse the old donut gasket from the driver's side stock cat (pry it off with a flat head screwdriver and reapply to the driver's side cat delete pipe). You will also reuse the old triangle gasket off the stock passenger's side cat unless you want to buy a 3rd new gasket from GM mentioned above.
Also FYI - 2M provides absolutely 0 documentation, instructions or anything helpful to assist installing these. I had no idea which bolts/nuts went where (they send different length ones) so I basically had to guess. Some of them are easy to figure out but some of them you're like... why is this different and where does it go?
2.) When you order cat deletes by themselves, they charge $349.99. If you order the header + cat delete combo, it's $699. If you buy just the headers alone, it's $549.99. Essentially, this makes it a much more valuable deal to order the header/cat delete combo because at $699, that's essentially only charging you $150 for the cat deletes as opposed to paying $349.99 for them separately. I chose to just buy the cat deletes only anyway because it's much easier to remove just the cats in case I'd need warranty work completed vs cats and headers. The headers were dynod by someone above and were shown to not really gain much HP, and they don't really do much for sound compared to the difference that doing the cat delete or sport cats do by themselves, so the headers just aren't a good idea to me.
3.) The cat deletes come with o2 spacers shipped to attempt to prevent a CEL. The o2 spacers do not have catalysts and are not mini cats, so there's a bigger chance of a CEL coming on. I will be using their provided o2 spacers to see what happens and will report back after driving it awhile to see if a CEL comes on. If it does come on then I will be purchasing one of the 45 degree o2 spacers with catalyst off ebay that people have reported to for sure prevent a CEL. I think I saw someone on this thread who said he used the provided o2 spacers and did not get a CEL so hopefully new ones are not needed.
4.) The job itself is a royal pain in the *** and not because of 2M but because of GM engineering. There are several videos out there on how to remove the airbox/cats and they all make it look way easier than it is. I won't go into full detail but I'll give you some gotcha's that will help make the job easier.
- Removing the trunk liner is the easy part. There are 2 separate liners, a rear and a front. Only the front has to come out.
- There are 12 10mm bolts total that have to be removed to get the airbox out. 4 are on each side of the airbox that holds the little arms in (the arms slide out towards you once the bolts are out). 2 are on the front lower part of the airbox, and 2 on the lower rear side. The 2 on the lower rear side are a pain to get to. I would recommend removing the clips first. I spent a good hour trying to remove the orange clips (there are 4 I believe, 2 on the front and 2 on the sides) and could not get any of them out even with pry/trim tools. I decided to just cut them. Then there are about 3 other black clips on the back side of the airbox. All of these can be pulled out by hand with a good amount of force. Once you have these off there's enough room to move the wires out of the way to get to the two 10mm bolts on the back lower side of the airbox.
- There's a connector on the front lower right side of the airbox that has to come off. Slide the red tab out and then I have no idea how I got it off but I spent like 15 minutes screwing with it and just got lucky to push/pinch in the right random place to get it off finally. There's also a connector on the back side of the airbox that plugs into a port on the rear side of the piece that connects the throttle body to the airbox (forget what this is called). Disconnect that and losen the clamp (on the back side of this piece, not the front side). Only the airbox will come out, the middle piece will stay connected to the throttle body.
- Loosen the o2 sensors before you unbolt the stock cats. They are torqued on there very tight and the angles to get to them are tough but can be done. I've seen most people remove the o2 sensors and disconnect them but I would just remove them and leave them connected because I couldn't figure out how to disconnect them from the clip. If you forget to loosen them before taking the cat out it'll be much more difficult to get them off later.
- The bottom bolts on the passenger side cat are going to make you want to pull your hair out. Not only because GM torqued all these bolts on with the force of 1000 Hulk's, but also because it's almost impossible to get to them. For manifold side, We ended up having to take off all the heat shielding to fit a wrench on it straight enough to get enough torque to remove it. We couldn't do it by hand so we ended up fitting a cordless impact in there and got it out. The cat back side bottom bolt is not possible to get to from the top from what I could tell. You can fit your hand under the exhaust to fit a socket on but can't get a wrench on it from up top. We ended up having to jack the car up a little and go from underneath with a long extension to get to it.
- Once the cats are out it's smooth sailing from there. Just don't forget to put all your gaskets on (There will be 3 triangle gaskets - one on each cat on the manifold side, and one on the passenger cat on the cat back side -- and one donut gasket on the driver's side on the cat back side of the cat. Remember to take the donut gasket off the stock cat.
I personally will NOT be reinstalling the 2 two rear 10mm bolts on the airbox or ANY of the clips. There are no moving parts on this side of the engine and all the wires are heat shielded so I don't think there's any chance of them getting burnt somehow. Once I start putting it all back together I'll see if maybe I can zip tie them for extra security vs just leaving them unclipped. I'll also report back on whether or not I get a CEL with 2M's provided o2 spacers.
Dom, I sure wish others on cf would be as thorough. I wish i came across your write up sooner... pre perf cat install. I ordered the $65 pair of triangle gaskets (paper quality) and looking at your write up, I see I need to remove the donut and the rear pass-side gasket off OEM. I sent 2M three messages, no response. YES, i found the bags of nuts, bolts, washers quite "intimidating" and four springs... now i see there for the heat blankets. My blankets came pre-wrapped and tied with metal wiring. Thank you for your post!.
header weight:
sport cat weight:
catless pipe weight:
I’m all for increasing and “improving” sound. But it would also be great to know if you are able to drop weight and how much.
Thanks!
this is '21 question so i'll assume u already have the info requested. If not or ur still thinking about this, the perf cats with blankets are substantially lighter. 6-10 lbs ea. Although I cannot say I'd reco 2M... for the reasons others have already stated. If I were to do this over again, I would spend a bit more and buy from other good-known sites.
It does get in the way but ultimately it doesn't have to come off. I was able to get to everything I needed to either by accessing from the sides or simply but standing/sitting in the trunk. I personally wouldn't want to remove the bumper if I didn't have to.
It saves a lot of time - if one still has oem exhaust. But more importantly, having it off really makes things quicker. The bumper is one of the easiest things to remove. I find that removing the rear wheels and lowering the lift so that the bumper can sit on the floor while disconnecting the three wire harness is a MUST. Two people helps but NOT required per this method.
Most sport cats shed 10-15 lbs. depending which core you go with. The Corsa/Cicio/Paragon/aFe cats all lose about 12 lbs. vs. stock cats w/heatshields.
I also have aFe Twisted Steel headers and combined with the Corsa cats I dropped roughly 25 lbs.
Are the collector on the Corsa headers full 3"? if so, what model are those? I've read some that Kooks supply Corsa with their 2.5" collector. And maybe only ARH are full 3"? I receved the Kooks and my fault for not doing more research but they're advertised as 3", the label and inspector initial states 3", the box states 3"... but true measurement 2.5", oem cats, 2M perf cats, OEM exhaust, aftermarket exhaust, are all 3" per my Stanly tape measure.
The 2M gaskets are trash. They crumble very quickly and youll have leaks along with the associated CELs. Save yourself the hassle and get 3 OEM triangle gaskets and a new donut gasket, theyre cheap.
I agree, the 2M paper(?) gaskets for $65 are ... :gasp and do not last even when putting the cats on.
Are the collector on the Corsa headers full 3"? if so, what model are those? I've read some that Kooks supply Corsa with their 2.5" collector. And maybe only ARH are full 3"? I receved the Kooks and my fault for not doing more research but they're advertised as 3", the label and inspector initial states 3", the box states 3"... but true measurement 2.5", oem cats, 2M perf cats, OEM exhaust, aftermarket exhaust, are all 3" per my Stanly tape measure.
Corsa & Lingenfelter have the same small outlet flange as Kooks. aFe matches stock header/cat flanges at 2.75" outlets. ARH is 2 7/8" outlets.
I have aFe headers + Corsa cats, typically leave for work around 6am, and have received "comments" from the lady across the street. Sometimes when I leave extra early, today for example, as soon as I fire the engine I'll quick flip to Weather mode until I idle out of the neighborhood which quiets it down a bit.
FYI, you can set your car to weather mode before you start by holding the start button for 10s, it enters 'on' mode where you can change modes before starting like normal.
I bought some used 2M sport cats from someone on here, but it didn't have the nuts/bolts/washers included. Can someone please tell me how many and what size nuts/bolts/washers I will need to complete the install. Thanks in advance!
After looking at the 2M sport cats on their website, they look smooth on the outside. I received these with the honeycomb pattern on them. They don’t look like the 2M ones. Did I get scammed??
After reading the thread I’m confused on which gaskets are needed for the header and cat replacement. I see what’s recommended for the bypass pipe but what about the cat+ header combo?
Last edited by The Great C8; Mar 29, 2023 at 03:31 PM.
I am STILL installing these - won't tell you all how long it has been - but DAYS... You must use the O2 spaces with 2M cats. I had four O2 flow errors - all minor and clearable. I have a HTC so it is reallllllly a pain. These cats are difficult to install if done by one person... Most cats have fixed bolts in them... that frees up one of your hands. I had this installed three times now, just trying to figure out how to position the spacers so that no more cel... The spacers with O2 sensor gets in the way.... wait for it, the great air-box!
The 2M exhaust are awesome... these and the exhaust are LOUD... So awesome sounding. The exhausts were a piece of cake to install but I am curious if the four NPP bypass chips from 2M will truly make them no cels either...
After reading the thread I’m confused on which gaskets are needed for the header and cat replacement. I see what’s recommended for the bypass pipe but what about the cat+ header combo?
The gaskets on the header/Cat side are GM 23194206. They are triangular ones. Gasket on the left is what comes stock between header and cats. Gasket on the right is what you need to use when switching over to the 2M cats
I removed my oem donut and pass-side gasket as per 2M email. The donut was cracked... Luckily local GM store had ONE left... I wasn't planning on reusing the pass-side gasket but it looked fine and I didn't want to re-thread the new gasket. After three assemblies and two disassemblies, the cels were all cleared! Hoot hoot. Time to put the car back together and back on the road!
