I posted earlier about considering uprading to x51 headers on my 02 C4s. I decided to leave mine alone. They were not that different from what I had IMO. I've seen photos of some of the newer headers on certain models that look strangled in comparison. A few observations: I was able to do the install without taking off the bumper. I also did it without taking off the exhausts or mufflers, whatever you want to call them. I applied a lot of penetrating oil to the hardware and in some instances used a torch to heat things up. The existing cats were not that much trouble due to being a two piece design. Putting in the one piece x pipe was more of a trick. There is no need to loosen the muffler tips. However I did cut off the long bolts that attach the muffler to the hanger assembly. The bolts are about 5.5 inches. I took the nuts off tapped them up to raise the head and cut it off with my dremel tool. You can't pull it all the way out at the top because of its length. Once I cut the head off I just tapped the remaining stub back in and pulled it out from the bottom. You are going to need a 7/8 wrench to remove the sensors in the cats. I went to Sears and bought one that had a short handle. The whole thing was about the length of my hand, maybe smaller, smaller than standard for sure. Once you remove all of the hardware, sensors and original cats you can wrestle the new one in there. I pushed the exhaust off its mouting point where I had cut the bolt out on both sides. (I used my foot.) This allowed me to push the exhausts far enough apart that I could push the new cat pipe farther in on one side than needed and manipulate the remaining length into the other side. Pay attention to how the mounting brackets were oriented in the first place and repeat. I updated most of the hardware with stainless and coated the threads in non seize coating. I postioned everything and snugged the bolts and hardware so it would not fall off. Once everything was in position I tightened it down. I replaced the long exhaust bolt with a stainless 6 inch bolt. This time I reversed the orientation inserted it from the bottom and placed the nut at the top. This eliminated the interference problem I had going the other way. The sensor on the drivers side that is closest to the 3 bolt connection where the exhaust meets the cat was a nightmare. They all were but that was the worst. After I removed it from all of the wire guide clips, I found that it was best to push it back up from where it was hanging and then have it come down on the other side of the bracket, closer to the back of the car. This was the only way I was going to be able to get it to work. I removed all of sensors from the clips that helped guide the wires. After I reinstalled the sensors I routed the wires through any clips that they could reach and looked to see of there was any potential rubbing. A couple of additional pieces of info. If you have big meaty hands this not going to work for you. Also, I already have a fabspeed exhaust installed. I am pretty sure the body of this is smaller than the stock exhaust. I could be wrong. I just don't know if this could be repeated while leaving the stock exhaust in place. One could certainly try and let everyone know. I hope this helps somebody. I drove it for about 5 miniutes afterwords. Really not that loud. Sounded good so far. I stopped because it was dark and feared hitting a deer while driving fast. I have hit two within a mile of my house with other cars. I feared my luck would be fix the cats and then wreck the car! I will update with impressions after I have had a chance to drive for a while.

 

Nice write up, curious to hear your thoughts once you have had the chance to break the new cats in. A sound clip would be nice too:-)

 

The five inch bolts you cut are not actually the mounting bolts. The mufflers attach via a plate with three 10mm bolts...pretty easy to get to.

To drop the old cats out, I removed the sensor wires from their clips and was able to just drop both cats out the bottom of the car with the sensors attached. Then you can remove the sensors with an end wrench...reverse the process for install.

I have a complete Fabspeed system with headers, 200 cel cats (not the x-pipe) and mufflers. Sounds very good. Add the cup CAI and you'll be really happy

 

I have the Fabspeed CAI. I saw the three bolts on the mounting plate. I chose a different route in order to not replace every nut and bolt. I replaced everything I removed with stainless just to make future work easier. If I get a chance I will post a clip with sound. The car does not strike me as being much faster. It does seem more willing to rev. I like the sound. I disconnected the battery for a couple of hours. I have read the cars have to adjust after equipment changes... we'll see. I didn't spend money on dyno pulls.

 

here is my install DIY.... FVD x pipe though...

http://forums.rennlist.com/rennforum...s-and-vid.html