My cat is plugged and im wondering if I just hollow it out, will it trip my check engine light? I've been told it might and i will get horrible fuel mileage due to this

 

Yes, it will trip your check engine light, at least it did on mine. I didn't notice a diff. in economy in my 3.9L

 

yeah i thought so. its a 5.2 in my truck, and it has duels from cat back..no mufflers, loud enough already but maybe i could cut the cat and put in flowmaster in its place. is there any way to trick the computer or the o2's

 

zip tie your rear o2 sensor to the frame out of the exhuast, it wont trip a code and gutting your cat will actually give you better mpg...

or use a SIM on the rear o2 sensor.. zip tie seems to work better.

 

Only thing that with no cats or muffler, you can be burning up your valves in no time. Best would be no cats, and a muffler, use something like borla or magnaflow, there are some tests out there that show the flow.

 

Single 3in, or 2.5 Duels, no cats, Spintech Mufflers... no problem with BP

 

Come again? I think you might want to double check your source on that.

 

+1

 

I just wanted to clear this up. The only way you will be busting (burning isn't the right word) valves due to exhaust, is by not having one all together...and I mean nothing! If you take everything including the headers off of your truck and run it for a while in cold weather, your exhaust valves can bend/warp and eventually fail due to the cooler air reaching them while being heated up directly prior to and following combustion. The extreme temperature differences can cause the failure, and not even all the time. As far as not having cats or mufflers, how do you think Harleys can function? Or even old school gassers and hot rods with straight shot headers? Not to call you out on this, I just wanted to make sure other people weren't being misled.