I am getting ready to redo my exhaust with a Flowmaster 40 series and dual tips. I want to replace the 4 cats with two high flow cats. I was just told that the exhaust place I am going to use will not install them because they will not get the emissons low enough to pass. I was thinking about going with the magna-flow cats. Can anyone tell me if they have replaced their cats and if emissons are still okay.

 

i was going to do the same on my 03- i tested the back pressure- on each side of the cats it was only 1 1/4 lbs of back pressure- at 5200 rpms iin gear under load-"may" pick up 2-5 rwhp by going to 2 units- only thing you 'll really gain is sound-phil

 

how much sound did you gain from installing hi flo's?
ive got straight pipes and im considering hi flo's to go along with them