Dealing with cats this week

[cprotzel]

I'm IE DP on my B8.5 sitting at 82k miles. Cats are on their way out. I think downpipe flex joints are going out too. The exhaust note is getting progressively louder and sounds worse every week. I got the car at 73k miles, cats were fine. Was IE SP for 75-80k w/one hard track weekend on that set up. Have been IE DP from 80-82k with no track time, just a few pulls around town. On the DP set up it has quickly blown cats and flex pipes that were probably weakened on the IE SP set up.

I picked up some stock downpipes with resonators from a forum member. The local shop I've been using will be installing those this week. They were $200 shipped and only had 35K on them. They look good. My original flex joints def need to be changed out and the original baby resonators sound like they are filled with sand/metal chunks when you bang on them. Probably cat material and baby resonator pieces.

The cats are going to be gutted and reinforced. I've read that the 02 sensor bung and the flanges are the spots where they need to be reinforced. Can somebody confirm this? How many welds exactly? I'll include a pic of one on of the posts I found on this with arrows pointing towards reinforcement spots needed. I'm in CA so I need to have the stock cats in, plus I hear the test pipes are too loud and don't have a good tone. I want to have the stock resonators in for visual inspection as well. I hear some techs think the baby resonators are the cats. I'm looking for a quietish exhaust that can handle a DP set up. I've got the Vibrant J 11619 J Spacers to deal with the cel. I've read that the middle spacer is the one to use. Anyone have luck with the middle spacer on these?

I'm putting in GESI High flow cats (50025) https://gsportbygesi.com/high-perfor...tems-products/ where the ECS X-pipe is. I want to relocate them downstream away from the massive heat where the stock cats are located. I talked to a rep at GESI and he said the 50025's can handle alot more heat than the 10025's, will completely eliminate smell, and are way cleaner than the 10025's they sell. Plus the 50025's are EPA certified. The 50025's are more expensive ($344.50 each) compared to the 10025's ($138 each), but I think it's worth it. Especially if I don't have to redo cats in the near future due to quick failing.

I'm leaving the rest of the exhaust stock past that point to the tips.

Do you think I should have them remove the rest of the exhaust and bang it out to see if there are cat/resonator pieces stuck in there?

Do you think keeping the newer baby resonators is just going to result in them getting blown out and spread through the exhaust again?

I'm hoping this set up works out so I'm ready for my next CA emissions test and I can run the 100 Octane IE tune during the next track weekend.

[hd1]

Good luck. Wish I had input. I'll be following since I've been IE DP for about 15k and at 92k. So far no issues, but I rarely keep the rpms high past a few gears.

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[cprotzel]

The low rpms are probably saving your cats. With the IE trans tune, it screams past 7k. I think with that high rpm and the DP set up it's cooking everything stock that's in the way.

[EIAlfonso]

I’ve had middle spacers for over a year, it’s the go to spacers and the one that you should start with
I have no cats


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[The_Bamboozler]

Regarding your cat welding question, you would simply put need 3 welds on each cat pipe; a bead around the o2 sensor bung, and a bead around each flange on the pipe.

The cats are welded internally and there are no welds on the outside of the pipe. Also take care to ensure your welder bolts down the cats to a bench/flat sheet of steel as the heat can warp the flanges and cause exhaust leaks if not properly tended to.

[cprotzel]

In my survey of the J spacer posts, the middle spacer seems to be the best. There are a few people that said the smallest diameter one worked for them. That's a good idea to start with the middle spacer and see what happens.

[cprotzel]

Thanks for the cat reinforcement info. When you say bead around each flange are you referring only to the inside part of the 2 flanges where the cat bolts up to the header and downpipe? Don't the cats also need to be reinforced where the actual cat is welded to the short exhaust pipe that goes from the cat to the flange? Good to know about possible warping issues with overheating cats.

[ANMS4]

I also blew my DP flexs out, I replaced them then replaces the cats with RedStar TP's with GSI cats. I also remove the suitcase and the baby resonators, Sounds very good IMO , I get compliments all the time, I run RS7 mufflers also

[cprotzel]

I also blew my DP flexs out, I replaced them then replaces the cats with RedStar TP's with GSI cats. I also remove the suitcase and the baby resonators, Sounds very good IMO , I get compliments all the time, I run RS7 mufflers also

Did you go with aftermarket downpipes or did you replace with stock downpipes/flex joints? The flex joints seem to be another weak link in the chain. I wonder if your GSI cats will melt being in the stock location. I haven't heard of any aftermarket cat that lasts over time in that area with a dual pulley set up.

[The_Bamboozler]

Thanks for the cat reinforcement info. When you say bead around each flange are you referring only to the inside part of the 2 flanges where the cat bolts up to the header and downpipe? Don't the cats also need to be reinforced where the actual cat is welded to the short exhaust pipe that goes from the cat to the flange? Good to know about possible warping issues with overheating cats.

Yes, you are correct that you would only need a bead around the flanges on the outside of the pipe.

Upon my visual inspection, I did not think that the cat to exhaust pipe connection would require an additional weld, but when you pull the cats, you will see that the flanges are welded internally, and the outside of the flanges does not have any welds.

[ANMS4]

Did you go with aftermarket downpipes or did you replace with stock downpipes/flex joints? The flex joints seem to be another weak link in the chain. I wonder if your GSI cats will melt being in the stock location. I haven't heard of any aftermarket cat that lasts over time in that area with a dual pulley set up.

I just replaced the stock flex joints, figure the originals last almost 90k mile if I get half of that from these I'm good :), the cats are a good question, my understanding is they will last, THEY BETTER for almost 2K!

[mys4.org]

I've heard that the 10025 were just as good as the 50025 and you were just paying for the EPA cert. I'm not sure what to believe any more. My gut tells me a sale person is always going to sell the more expensive thing, but who knows. That said I want to do the same thing and gut the stock cat and add the 10025's to the bottom end of the down pipes. I figure if I can get them as close to being parallel to the ground the air flow under the car should help dramatically keep them cooler then tuck up high near the engine. Obviously they will take longer to warm up and be a little more expose to the road, but oh well..... The should be easier to access if I need to replace again.

[cprotzel]

I just replaced the stock flex joints, figure the originals last almost 90k mile if I get half of that from these I'm good :), the cats are a good question, my understanding is they will last, THEY BETTER for almost 2K!

Yeah i'm hoping to get some miles out of my newer flex joints too. I don't drive much so that should help. Though more track days will push them to the limit. Unfortunately these cats go out even on stock tunes. With stage 1, 2, 2+ they have a serious chance of failing. Though there are a few people with stage 2 on stock cats for years. Not sure how that happens.

[cprotzel]

I've heard that the 10025 were just as good as the 50025 and you were just paying for the EPA cert. I'm not sure what to believe any more. My gut tells me a sale person is always going to sell the more expensive thing, but who knows. That said I want to do the same thing and gut the stock cat and add the 10025's to the bottom end of the down pipes. I figure if I can get them as close to being parallel to the ground the air flow under the car should help dramatically keep them cooler then tuck up high near the engine. Obviously they will take longer to warm up and be a little more expose to the road, but oh well..... The should be easier to access if I need to replace again.

I talked to a team member at GESI cats and he gave me info about the 10025's vs the 50025's. He wasn't a sales rep so wasn't trying to upsell me. He said that there is a different furnace brazing process with different chemicals in the 50025's which allow them to withstand higher temperatures and are much cleaner. I don't want myself or my family to have to smell anything or be exposed to any more toxic chemicals so the 50025's were a must have for me. If the extra few hundred bucks means I don't have to go back in there and replace anytime sooner, it's totally worth it. But the 10025's are decent too. Just not on the same level as the 50025's. Installing them under the car near the end of the downpipe will probably make a huge difference for cat cooling and ease of replacing.