Has anyone installed the PAcestter header on a 2.5 liter 4 banger. Pro's and Con's heplful. I already have cat-back and cold-air intake, and new catolitic converter. Will the header let it breath more and gain a little bit of ponies to boot?  

Not sure about the 4, but the I6 comes stock with a header.  Have a look, it might not buy you much.

Pete  

Honestly, I don't think the gain would warrant the price.  The gains will likely be so minimal you may not even notice them.

I would recommend trying a 4.0L TB swap first.  You can usually pick one of them up at a junkyard for a lot less than a header.  Even still, the best way to help your motor is going to be gears.  Compared to the cost of all the exhaust and intake stuff that people do you're going to get a lot more gain.

You didn't metion if you're running any lift and or larger tires but if so I stronly recommend you save up a few extra bucks and get your gears upgraded before you put any more $ into the motor.

This is all strictly my opinion so take it for what it's worth.  I have done the headers, cat, muffler, and cold air intake and had marginal power gains with my 4.0L.  I failed inspection for my exhaust and had a crack in my stock manifold so I had to swap out these parts and personally believe that upgrading was the way to go. 

My opinion, if you're looking for more power, get gears.

I must agree.  I did cat, muffler, intake, complete tune up, o2 sensor, etc.  I still failed the first time, and it took a injector flush and decarbon (whatever the heck that is) to get the damn thing to barely pass.  

I have heard that chrysler products are not so good at passing emission test ... but that could be wrong.

Pete.