Originally Posted by my89xj

I'm so pissed. The cop that tried to arrest me for my "gun" made me put my doors back on, since I was on the school parking lot, and wouldn't let me leave until they were on, so I put them on, parked on the street and took them back off. She yelled at me again so I left.

Originally Posted by mikefrost

Such a rebel LOL

Originally Posted by my89xj

I'm so pissed. The cop that tried to arrest me for my "gun" made me put my doors back on, since I was on the school parking lot, and wouldn't let me leave until they were on, so I put them on, parked on the street and took them back off. She yelled at me again so I left.

Originally Posted by kuzican

at that point, just as long as you have mirrors (driver side and rear view) tell them that it is not illegal and they can't do anything about it.

Originally Posted by kuzican

at that point, just as long as you have mirrors (driver side and rear view) tell them that it is not illegal and they can't do anything about it.

Originally Posted by kuzican

at that point, just as long as you have mirrors (driver side and rear view) tell them that it is not illegal and they can't do anything about it.

Originally Posted by gone4x4

--might not be sage advice, i think him just leavin was the smartest thing, he is though, a marked Jeeper!!

Originally Posted by my89xj

I'm printing out were it says that and talking to her about it tomorrow. And ill have no exhaust on tomorrow since my magnaflow cat just came in the mail

Originally Posted by jimmy21669

I'm going to try to cover this without getting too technical.

The stock exhaust is a compromise between efficiency, power and quietness and does have a considerable amount back pressure. In this case, the back pressure actually aids in quieting the engine, but decreasing the torque.

Back pressure is not an engines friend as it causes hot exhaust to remain in the engines exhaust port for a longer period of time. Granted, it just for a fraction of a second, but that's all it needs.

A well balanced exhaust system will have a 'tuned' exhaust manifold, exhaust pipes of sufficient diameter to maintain exhaust velocity and cat and muffler with minimum restriction.

A 'cat back' system generally refers to the components after the catalytic converter. Reducing the restrictions of the muffler and tail pipe will improve engine torque. But, the cat still remains as a restrictive device and can be solved by replacing the stock converter with a high flow version.

The stock cat has sufficient restriction to maintain the burn in cleaning up the exhaust. This is probably more true of the '97 and newer XJs with the dual O2 sensors. However, a high flow cat is designed so that the exhaust has less restriction while doing a proper burn.

A tuned exhaust manifold is designed so that as the cylinder releases the exhaust gas it aids in pulling in the next air/fuel component, called 'scavenging'. It does this by having timed equal length exhaust tubes.

To clarify this, as one cylinder pushes out the exhaust, the next cylinders exhaust won't collide with the previous going out the exhaust pipe. For illustration, look at the 4.0 aftermarket exhaust manifold. You'll note that cylinders 3 & 4 are closer to the exhaust pipe port than 1 and 6. In a factory manifold, the exhaust is just dumped into a common pipe and the exhaust exists the best it can. With the referenced manifold, each pipe is designed in length and diameter to reduce exhaust collision and exit freely.

On the math side...once it is all said and done...the 2.25" exhaust was engineered to balance the scavenging/exhaust velocity of the 4.0 head. If you had a stroker, high flow head, I would go 2.5". However eliminating restrictions after the muffler can improve the torque curve. The problem with the stock system are the bends that were put in the downpipe, tailpipe and the restrictive stock cat and muffler. By going to mandrel bends and high flow, you will achieve the best of both worlds with 2.25 through to the muffler with all freeflowing components.

That's all I'm going to get into here. If you want to learn more here are two excellent articles (and not too complicated) that explain in detail the exhaust flow.
http://www.veryuseful.com/mustang/tech/ ... enging.pdf
http://www.bigcitythunder.com/pages/und ... xhaust.pdf


EDIT...damn second link no worky no more... :-(

Originally Posted by kuzican

at that point, just as long as you have mirrors (driver side and rear view) tell them that it is not illegal and they can't do anything about it.

Originally Posted by my89xj

That's what I said, I'm printing it out, were can I find that info?

Originally Posted by Courtjester

So I saw the body armor I want does anyone know who makes it.

Originally Posted by a_shirey

you're such a terrible student. better than ripping down speed cameras like at my school or shooting someone...

Originally Posted by mikefrost

Here's a set of 2x4 sliders I just built. Getting ready to Raptor line these

Originally Posted by Bohnett

Looks good Mike. We should set a trip for Rausch in September?? I think I'll come up next weekend if your there, want to have a cookout? I got some jeep fixin to do and I can help with yours..

Originally Posted by jimmy21669

Could be detrimental to your health in the long run....