backpressure is how much the air being pushed out of the engine is being held up in the exhaust due to bends and restrictions. So, the more bends and things like cats that you have the more backpressure you will have. And you can feel the backpressure because it can hold the truck back... I notice when i reduced the backpressure that I had a lot more power from the freed engine but my mpg went way down...
And when i put my 44 in i didnt take any cats out... all 5 cats are still in and then the 44 and then out lightning style... preforms and sounds great coming out of my truck... and my 44 will last forever, glasspacks wear out overtime and get blown out. that sounds terrible when it happens trust me!
2003 Ford Ranger Edge 3.0L Vulcan Auto Tranny
MAC Performance Ram Air Intake
Flowmaster Super 44 w/ tailpipe before the wheel
Interior and Exterior LED w/ music interface
Ford Racing front and rear Sway Bars
Limited Slip with 4.10 gears