Exhaust help!

[mark2215]

I'm in the final stages of planning for my engine upgrade. Right now I'm running a Ripp supercharger and will be putting this on a Golen 4.6L boosted stroker motor and making 350-400hp. The last thing I have to figure out is exhaust. Golen recommends JBA headers, is this the best? The only pre-cats and downpipes I can find are factory, is this my only option? I'm going to find a local shop to make up the rest of the system. What size should I go and any recommendations on muffler and cat?

[SilverXJ]

There are aftermarket precats. However, stay away from walker. I believe there is a company that makes a high flow version, but I can not remember them off the top of my head. Your other option is to eliminate the precats and sim out the O2 sensors with sims or have the PCM modified to remove the down stream O2 sensor monitoring. AFE, JBA, Borla, Pacesetter, OBX and anks all make headers for the exhausts with pre cats. IIRC Clifford also has an interesting header, but it is a lot longer. I would go with 3" single exhaust. Or if you want to go duals, 2.5". Personally I try to stay from a dual exhaust on Jeeps as its really tight and adds weight and complexity.

[SilverXJ]

I'm also in the same boat as you. I'm putting an MP90 on my stroker and currently have an earlier style header on my 2000 w/ a 2.5" output and 2.5" all the way back. I'm debating on staying with the 2.5" or going larger. Then there is the question of if the 2.5" header will be a significant bottle neck.

I would also get in contact with those companies and see what their collector sizes are. What I have says the JBA are 2.5"

Here is some info: http://www.magnaflow.com/07techtips/faq/question10.asp

[wjtom]

The pre cats do not need to be there and it wont pull codes.I dont know about passing a state inspection where you live with them removed .If it became a problem where i lived i was going to drill mine out and slide the shell over the new larger head pipe i made so it looks like they are there.By accident i came across an old tsb where they had problems with them setting codes with low mileage and from what i can tell made the parameter so big it wont pull a code for them anymore after the pcm reflash.Mines been like this for 2 years and no problems.I wouldnt recommend the obx because if you have to remove it in the jeep 2 of the bolts are almost impossible to get back in much less see.Although it does have 2 1/2 inch outlets.

[mark2215]

So I've decided to run the JBA headers and stock pre-cats but run 3" after the pre-cats and eliminate the third cat. This is what Golen recommends because there are 2 pre-cats so they don't need to be 3" like the rest of the system. Does this make sense? It'll also save me from having to mess with all the o2 sensors.