I have an 06 monte ss with zzp catless dp and slp resonators on a 3in exhaust system, wanted to add a universal high flow cat after the down pipe, can this be done without causing any kinds of problems ? And has anyone done anything like this ? New to the forum looking for advice and tips thanks for any help.

 

Just curious, why not add it to the down pipe where it normally would be?

 

Should I just have the dp cut down and have it installed up near the manifold then ? Also any recommendations for a high flow cat I was thinking either kooks or flowmaster https://www.summitracing.com/parts/kok-ge-307540/. Thank you

 

Couple options - you could sell your DP and just buy a DP with a cat. Would be more expensive, but you could easily DIY it.

Another option is to pick up a cat and have a shop install it where it would normally go - leave the DP connected on both ends, hold the cat up there, chop out that section of pipe, and weld the new cat back in.

TBH, I'm no expert with high flow cats, I've never used them. What are you trying to accomplish by adding one? Are you just trying to cut down on some smell, are you looking for a legitimate full functioning cat, etc? Only reason I ask is that not all cats would pass tailpipe emissions in all 50 states. May also make it difficult to find an exhaust shop to do it if the cat you're trying to put on clearly says that it's not for emission controlled vehicles.

 

Yeah so plans had changed I’m just now getting my car out of storage from the winter, I’ll be driving it as my daily driver from here on out and I wanted to have it running better than stock (nothing to crazy) but still keeping the car in mint condition. I no longer want to pollute everywhere I drive and the car is too loud for what it really is especially if i will driving it everywhere I go. I was looking for a way to cut back on the noise level and stop producing harmful emissions and keep the vehicle as healthy as possible and try to prevent future problem. I know a muffler shop that would do this work if it’s possible to be done. I just want to know if it’s my best option. I have a mini cat cel fix to take care of my check engine light and I could go buy some borla mufflers if the high flow cat isn’t even worth it. I’ve heard they fail on people.

 

Also any other things I should need to know before going through with this. I already have a new o2 sensor and I was planning on buying a heat shield for the cat as well and if anyone has ever done something like this and all was good. Thanks for the advice though

 

I'm a bit confused as you're talking about 2 different issues and fixes. Mufflers will fix your noise issue and a cat will fix the pollution issue. A cat will do a little for noise, but it would have to be pretty close to the sound volume you're looking for to have any hope that it would fix both. Of course mufflers would do nothing for the pollution.

There are quality high flow cats out there that wont have issues. Also, if you aren't very heavily modded otherwise, a stock cat would be fine too and would do a better job with emissions.

As far as the 'best' option, I dont really think there is a clear winner here. Below are my thoughts on the choices:
-A stock cat and downpipe would be the cheapest option and the best for emissions. You could pick one up on the forums for cheap from someone who went with headers.
-A bolt in catted downpipe would keep the performance benefits of a DP with bolt in simplicity. You could knock it out with a Jack and ratchet in 30 minutes.
-Welding in a cat would have the small performance benefit of the above (I'm assuming you have an aftermarket DP / cat delete) but would let you (or your exhaust shop) choose whichever high flow cat has the best reviews. There's more labor here and more chance for failure with 2 extra weld joints.

 

Thanks for the advice