Did you guys took off the catalytic converter when you did your exhaust? They say that the catalytic don't let the engine flow smooth. But if you take it off the check engine light comes on.. So what do you guys have done? Do you live it there and start the piping from the cat. back?

 

left them on.

 

our 4.0s sounds like as*hole with out em....

 

Get some high flow cats....


I really wouldn't worry about your cats unless you were going f/i... and even then only if you're pushing like 400hp or something

 

What about the the pipe that is between the headers and the cats? should i leave them like that or should i have them replace for a bigger diameter since I'm installing new headers too?

 

There are no pipes between the exhaust manifold and cats. The cats bolt directly to the manifolds

 

I weas referring to the little pipe that connects the headers to the cat. where the first oxigen sensor is located.

Another questions... How good is our fuel pump? will it be necessary to change it in the future if some major upgrades are made to the engine ( is the GT fuel pump better)?

If I'm asking all this questions is because I saved some money and i'm doing all upgrades that i can at the same time ( no no xcharger yet).. I already have 8.8 axle, 3.73 gears, flow masters, headers, and intake ready to install and waiting for SCT-3 Bamachips tunes...

Thanks guys for your replies..

 

i took my cats off, but like others said it does sound like ***. i dont feel like running the risk of them falling apart with me pushing 400-500hp.

the fuel pump is fine. i still run the stock one without even the wiring upgrade done to it.