i recently have had a real big loss in power with a loud air noise coning from my 1500 5.2l its 4x4 ext cab ive only been able to go about 45 mph so i went under the truck and took a look and noticed that the air noise seems to be coming from a slot in the pipe just in front of the cat its about the size you would stick a quarter into where it came from idk if it was there all i know is the noise is new all that said heres my question anyone know what size pipe that is right befor the cat im planning on getting rid of it so i need to know what size pipe to get 2 could this slot be messing with the pressures enough to creat the loss of power since only one of the two pipes has the slot? and could the plenum be causing problem with it as well?

 

is the pre cat o2 sensor still there ?if so pull it out see if that helps. sounds like you may have a clogged cat .

 

yep...chop off the cat and run her straight and see how it works.....I would bet the farm it's plugged .