Ok so right now I have a flowmaster SI/DO with turndowns and no cats with both resonators (was on truck when I got it). I'm looking to get a little better gas mileage and performance if possible but I'd rather have gas mileage over anything and also a better system to help the motor. I'm looking to get either a magnaflow Y pipe with a SI/DO muffler or magnaflow X pipe with 2 SI/SO magnaflow mufflers, and a magnaflow cat. I say magnaflow because I read there a better performance muffler then flowmaster. I was wondering what y'all think?

 

Best option is a mix of the two: 2.5" from after the cats to a DI/DO Magnaflow. The DI/DO have an "X" in the body, where the two sides can "equalize". Using the "X" pipe and two mufflers would likely not yield any more mpg or horses than the DI/DO would.

 

Ok so your saying get a magnaflow x pipe, 2? Magnaflow cats and a magnaflow DI/DO muffler correct?

 

The stock cats flow plenty well. No gains to be had by upgrading them. What I'm recommending is removing everything from after the cats to the tips, and replace it with 2.5" SS pipe and a DI/DO Magnaflow. I had a shop do that for me, and the cost was around $300.

 

The stock cats would be fine but they were not on there when I bought the truck so I'll have to get new ones.