1. OBD I was less technically advanced. The simple means of injecting air into the converter was the method used to burn the unspent fuel in the exhaust system | 
2. GM's 4.8- and 5.3L engines in both '99 and '01 trucks used the round-style catalytic converters. These cats were prone to failure and actually had a tech bulletin placed on them for replacement if failure occurred. If your truck is running the round cats and you have a problem with them, call GM on the posted bulletin, because you might get them replaced free of charge. | 
3. Here's GM's fix to the round converter issue. The elliptical catalytic converter supplies additional surface area for added catalyst, providing additional durability and flashing. |
4. MagnaFlow uses a SuperFlow bench to measure the performance of each converter. The stock converter flows an average of 279.93 cfm, with 28 inches of vacuum being pulled through the cat. This is about 29.6 percent of the available airflow. The bad cat we used for comparison flowed an average of 220.37 cfm at the same SuperFlow settings. | 
5. Here's one of the things that makes a huge difference between stock and MagnaFlow's cats. This catalyst used in the performance converter obviously provides more flow. Yet, the material used by MagnaFlow provides equal to superior gas evaporation at the same running temperature. | 
6. The CARB-legal cats can be adapted to a variety of powerplants. MagnaFlow has passed cats that can be fitted to any of the major three domestic automotive manufacturers. The import market will be the next on its list of cats to tackle. |
7. GM uses two cats with four O2 sensors, before and after, to comply with the OBD II standard. | 
8. As we said before, GM's stock cat flows 279.93 cfm on the flow bench. At the same settings, MagnaFlow's CARB-compliant cats flow 355.0 cfm. That's a substantial increase in flow. | 
9. Dodge uses the same twin cats with four sensors. This is the simplest, cheapest way of implementing the OBD II standard. |
10. The stock Dodge converter flows a little better at 309.93. Of course, this is largely due to the fact the Dodge uses a 3-inch exhaust tube providing more flow. MagnaFlow's 3-inch performance cat flows 408.87. | 
11. Some people just need to be different. Ford uses the four sensors, two before and two after the cats, but the work is broken up by using four catalytic converters in the exhaust systems. It's hard to compare the three trucks because the tube in between the four cats on the Ford is an added element in the test, which makes the comparison unfair. We do know that the added flow from the MagnaFlow cats is a loved mod for the Lightning. | 
12. Mandrel-bent tubing and thick flanges make the bolt-in kits better because they frequently eliminate the pinched tubing the manufacturer uses. |
13. MagnaFlow's bolt-in kits are few right now, but you can bet it will be expanding the line of OE-legal bolt-on kits to make the install consumer-friendly. | 
14. Also offered is MagnaFlow's line of Race Cats. They are made of stainless construction and use a stainless catalyst. These high-flow cats are actually at the CARB now, in hopes of getting the big stamp of approval from Uncle Sam. We most certainly hope these pass the test. Not to be outdone, MagnaFlow also makes a cat for the diesel lover. There are no numbers on this monster because it out-flows the bench for obvious reasons. | 
15. Here, you can see the difference between stock, performance, and race cat airflow, measured at MagnaFlow. The stock Dodge has the highest airflow numbers between the truck line. Stock, the Dodge flows 309.93 cfm, while MagnaFlow's High-Flow Performance cats flow 408.87, and the Race Performance cats flow 597.97. Two of these cats could potentially have enough flow to allow for 1,200 horsepower. |
16. So what's to be expected of the high-flow CARB-legal cats in the performance realm? That's completely up to you. These performance cats definitely provide more flow for forced induction, and other mods will benefit from them as well. Here is a dyno run that overlays a stock truck, stock with after-cat, then finally stack with after-cat and High-Flow Performance cats. | | |