xjforlife

This is where I got the idea from now he ran no cat but believe it or not mine sounds exactly the same but about 10% quieter

swampxj86

If you are getting a Dorman manifold and you want to get from a local store use the TRT30 code and get it 30% off at advance auto parts

GUARDIAN

2004 wj, 4.0, k&n cai, borla cat back. Now for the "bad" part, california emissions. Was going to put header on but don't know if it's worth it. Live in nevada and have to pass smog. Would it cause more problems than it's worth to eliminate the pre cats, go with the header and relocate the o2 sensor? I'M WONDERING IF THE COMPUTER WOULD THINK SOMETHINGS UP AND GO NUTS.

jeepkid03

Yes it would be more trouble than its worth. The Cali emissions Jeeps have 4 oxygen sensors, 2 for each mini cat. The sensors monitor the efficiency of the mini cats separately.

They make headers that will work with the mini cats and replace the two piece stock manifold on 2000 and newer 4.0s.

Badmunky

If your going to replace the entire exhaust system on a 2001 4.0 XJ, can you use a header meant for a 98 4.0 XJ?

jeepkid03

If it has 4 oxygen sensors, then no.

rarmstrong

I just installed a ZJ gas tank skid plate that I got from the JY. It fits nicely but the exhaust mount is now flush up against the side of the skid plate. I'm concerned that this will transfer more heat and eventually wear a hold in the side of the skid plate.

Any ideas on how to fix this?

Also, the forum reviews I read were showing a heat shield between the gas tank and the exhaust. My 94 XJ did not have one of these shields in it when I bought it. Are they supposed to be there or does this year model not have a heat shield?

See pics below.

thanks in advance!

austinjoe13

I highly doubt that will be a problem. That looks like it's gonna rattle down even the smoothest roads though

jeepkid03

See if you can get a clamp that isn't as square or grind that one down a bit.

rarmstrong

Surprisingly so far no rattling but I have just driven around 2 days. I'm thinking of modifying the isolating clamp that bots to the skit plate, to push it out a bit. Alternatively, put some kind of isolation between the skid and the lower part of the clamp (like a piece of old tire).. not sure if that would work.

rtralabama

since reading through this whole thread will take a month, anyone got any good high flow cats they are running, i got a 2000 4.0 with california emissions. pre cats are fine for right now.

triplets_red_xj

I have a magnaflow cat on my 98, there is only the 1 in front of the muffler, none in the manifold, not sure if it would work for yours, it was like $120 on Amazon

Dumajones

try this place

http://performance-curve.com/thunderbolt-spincat.aspx

rtralabama

i like their prices...thanks!

Z.paul17

has anybody used pacesetter quik-trip exhaust manifold? if so are they worth the money?