Just got one today and put it on, and man is this thing loud. I hope I can put up with it. Now the only thing I need to do is figure out if I want to put the Aero 4040 or 4040xl in place of the cat. I noticed a big difference on top end pull, buton a highway pull when it hit about 2600-2700 rpm it felt like the truck gained another 2 cylinders. It felt about the same as before untill that rpm range. Is that sound about right, because I sure wouldnt mind it pulling that hardin thelowerrpms. Also is the Pro gaurd 7 a oiled filter, didn't seem like it?

 

i believe it is an oiled filter. if noise is an issue than from what i've read and seen the 4040xl is what you want for exhaust. someone will chime in with a definate on the oiled filter i'm sure.

 

yeah the XL has th baffle which would eliminate most or all of the drone you could get with the 4040 because the 4040 is basically a cherry bomb for diesels. LOL