im trying to straight pipe my buddys 93 cherokee. i dont know the size of the pipe going into the muffler, and the pipe going out. were not sure whether were going to cut the muffler and just put a piece of pipe their, or do a side dump. any help would be appreciated.

 

A tape measure will eliminate guess work.....never know what a PO may have done.

 

Stock is 2.25.

 

Run an aftermarket muffler, don't do a straight pipe. It sounds kinda funny IMO. Also, keep it goin all the way to the back like original. Usually a side exit or turn down is illegal. If you do a muffler, make sure that it either has the same inlet and offset position or you get a pipe bent into an S so everything is like original and clears all the important stuff under there. I don't entirely know if a straight piece of pipe to the tailpipe will still let the tailpipe clear. From the looks of it it may not clear or may be very close. If you go with a straight pipe and no muffler, also get an S bend at the right measurements.

 

thanks guys. so to storm101, 2.25" is stock all the way through, or does it change? and is that ID or OD? and is 2.25" into the muffler, and out? and to XJ.89.Limited, i live in PA. side dumps and turndowns are ok, as long as it goes past the last passenger seat. and my buddy inspects all my vehicles, so he would take care of it anyway.

 

if wanting to keep it legal and sounding good go with a 3" pipe after your headers, get the pipe all welded and done nicely into a hiflow catalytic converter then a flowmaster 44. u wont be disappointed. 4.0's like back pressure so personally i wouldnt run a straight

 

2.25 all way unless the muffler was changed previously. I say measure it up if possible. Measure the circumference and use a simple geometry formula to get the diameter. I don't remember the formula but google can probably help you. As for the exhaust, we're better off goin to the tailpipe. The rear seat is right on the rear tire. The law states that side exits and turn downs are okay as long as gasses cannot enter the passenger compartment. Which is the whole thing unfortunately. I was gonna run a 90 degree bend and a side pipe but the law won't let me since it would come out right under the rear door. If your buddy can pass it, go for it. I don't have any connections.

 

C = 2πr2

r = d/2



To find diameter, you'd rearrange the Circumference formula to (square root)(C/2π) = r, then multiply r by 2.

 

C=2?r not C = 2?r2

 

CF messes it up. It's C = 2 times pi times r (squared)

 

i just got dumber trying to read that formula lol. i have no idea what i was reading. ill just figure it out someway. and yes, i have connections to pass my cars, so it doesnt matter what i do to it. as long as its not sloppy.

 

Just given you a heads up. Keep the cat, or at least put a high flow on in. Discussing cat removal is frowned upon here: unacceptable, and the thread will be closed. Also, removing your cat is a federal offense. Not trying to blow the legal trumpet, just going by Da Rulez and Lawz.

 

first off, i didnt know that talking about removing a cat would cause the thread to be deleted. second, talking about something and doing it, is 2 different things. and third, i never said i was going to remove a cat. im asking options on straight piping the muffler. some other guy said about removing the cat. plus, y would i make more work for myself lol?

 

It's just some advice, chill out. We don't take stuff like that nicely. A simple "I didn't know that, sorry" would have worked :P

 

Just so you know, you can also get a ticket in PA for not having a muffler, and especially for not having a cat, even if your buddy can pass your car, cops can still hassle you. Not saying not to do it, I've done muffler deletes on some cars, just a warning. Also a Jeep 4.0 will be absurdly loud and sound like **** without a cat or muffler. Think......ricer meets tractor, thats what it will sound like, and it will drive you crazy inside it.