Ok, just had Midas (never use them again) weld on my new high flow cat. The cat is a carsound universal 94100 series.

Since i've had it installed (2 days ago), my car feels conjested, aka, air is not flowing nearly as good as it should from the exhaust. It sounds like the car is "huffing" air at mid to high RPMs. Pick-up seems to be noticably deminished. The cat itself is 2.5" dia, stuck between a Greddy header and a Apexi WS exhaust, so I know the cat should be able to handle the flow.

Tonight I'm gonna jack up the car and take a look to see if dude put the cat on correctly, his welding job was **** poor (he blistered the metal, that clinches it, I know I can weld, I'm gonna get me a TIG or MIG). Also, I'm gonna see if he cracked my header. he cut the cat off the car (even though it was bolted on), and then welded the used flanges from the old cat on the CarSound one. When he was cutting my old cat off, I was watching the entire exhaust sytem shake like mad, that can't be good for the header.

In my mind, right now, the cat itself is prolly not the culprit. I believe either the header got damaged or dude put the cat on backwards and the "mushroom flange" in not hooked up the the header.

Please let me know what you think, as i've never had a busted header, and this is only my second high-flow cat.

also, if the carsound 94100 is a "limiting flow" cat, please let e know what you would recommend
so I can check it out.

Thanks a lot.

 

I know this isn't helpful to your situation, but I'd just like to offer a suggestion for next time. For close to the price of a universal Carsound and installation (labor, flanges, etc.) you could have a Carsound custom built to your application, with high-quality welds and materials, then just bolt the whole system together. Pictures of the installation would be helpful in determining where any bottlenecks/obstructions might be. However, one obvious problem that I can think of is the extremely small size of the stock flanges that you say were welded on to the new cat.

 

Thanks, that is a good idea. where would I go about doing this, getting a custom CarSound cat welded on?

Oh, and my flanges are oversized I had them machined by a friend at work (we make museum exhibits, so these were perfect, and industrial strength - I had them on my old cat, and had them used again on the new cat). The problem is with the flow.

 

Dave at SMSP should be able to make up basically any sized Carsound you need. Since neither the header nor the cat-back are 2.5", I'm interested in how the reduction occurs. Is it a smooth taper, stepped, etc. I'd still be interested in seeing pictures of the installation. Even a cracked header shouldn't cause the type of flow-loss that you are describing. What was your setup before this? Maybe your butt-dyno is just misinterpreting something.