the stock exhaust is 2in so if i got to 3in will it be louder or do u have to go smaller to get it louder?

 

It will probably get deeper witht he bigger pipe... if you use a smaller pipe it will be more high pitched. The "Loudness" is controlled by the muffler.
Honda with stock exhaust... quiet 1.5in pipe
Mustang With stock exhaust quiet 2.5in pipe
^^^^
May be a bad example but I hope you get the idea..... and that I am right

 

you dont want to go to big or you'll lose back pressure and low end tq

 

I just did a 2.5 catback on mine and love it so far im also running a single chamber flowmaster as well as keeping the stock cat. for now.......

 

rhino thanks for the info thats exactly the kind of info i was looking for

 

no.....

although a chambered muffler is louder, if you throw a stock 2.25" tail pipe on it, it wont be as loud as a 2.5" one. the larger the pipe, the slower the gas, the greater the resonance of the gas.

 

My Jeep had a 2.5" cat back with no name turbo muffler when I bought it. It sounded like a vacuum cleaner. I put 2.5" "S" pipe back with a Flow Master 40....it got louder.

 

if you open up the exhaust. you should open up the intake and vise versa.

do a cold air and a cat back with a nice flowmaster and it'll sound nice.

 

im not sure what u mean by open up the intake
and not sure what a cat back is

i'll google it, but if u can add some more info a or thread link that has the info it would be appreciated

 

by intake he means the air intake like a cold air intake, and cat back refers to an exhaust that bolts on and replaces the stock exhaust from the catalytic convert back

 

^yup, sorry.

to inhale more air, you gotta be able to exhale more air. and visa versa.
if you do one, you should do the other.

 

that wont be an issue the o2 sensor will compensate
its a big issue on non computer controlled cars

 

thanks guys ill give it a go when i have some free time

 

how the hell is the 02 sensor going to compensate for loss of power?

 

It will compensate, but not that much. With a stock or mild modded 4.0L 3" is WAY too big. There will not be enough backpressure. But, You could go 3" after the cat to give it more sound. The inlet of the cat is 2.5" and the cat should give enough back pressure. But 3" all the way from the mani/header =fail