Finally took the plunge and ordered and installed some RV6 High flow pre-cats. I was considering the pre-cat deletes for the longest time but after some research I decided the High flows were the best option, especially considering I had already hollowed out my third cat. The deletes from my research seemed to get a lot of rasp especially with the third cat deleted, while they do make more peak hp a few dynos show High flow actually make more average hp and TQ. I would be combining the HFPC's with the RV6 J-pipe that I had already installed. I am very please with the quality of the pre-cats and the hp/tq results, same goes with the previously installed j-pipe. The truck pulls so much harder all the way from idle to red line, I felt an instant difference pulling out of my drive way. The exhaust has a bit more rumble when getting on it but still very quite at idle and while cruising, which is exactly what I was after. I'm figuring with the j-pipe and HFPC's i've picked up close to 30-35whp and about the same in tq.
Total install time from start to finish with tools put away was 3 hrs. It went incredibly smooth almost to smooth. I did not remove the pass side axle as the owners manual suggests for the rear pre-cat. I simple removed the factory heat shield and removed the factory pre-cat from the pass side wheel well. It is much much easier this way IMO even if just replacing with a factory unit I would still do it this way. Also I should add that I live in FL and do not have to deal with rust issues which if you live in the rust belt I'm sure this job would be much much harder. I have also had my j-pipe off recently and also replaced all 4 o2 sensors recently, being familiar with both of those jobs made this job much easier as well.
Heres a link to my j-pipe post. Its post #180
A link to the RV6 website. Keep in mind only the 06-08 currently have a j-pipe available, 09+ there currently is no j-pipe for them.
A few links to dynos and hp/tq claims of HFPC's.
Yes those dynos are not on an RL so yes hp and tq gains will be slightly different. Yes most dyno's of HFPC's mostly only go from 3,000 rpm and up, Yes the biggest gains are on the top end, but I can assure you low end tq is also improved greatly. I noticed and instant difference down low with just the j-pipe and even better when combined the HFPC's. The truck just pulls like a beast now from idle to redline, takes very little throttle while cruising to pick up speed, don't have to force a downshift to get this beast moving anymore.
I don't have a complete list of tools or pics of every single step I took but I did the best I could as I know there are not any threads with any great detail of this mod or removing/installing factory pre-cats. The rear cat is very hard to see and get pics of so I did the best I could.
Your main tools you will need are 10, 12,13, 14mm sockets short and long sockets will be needed. A couple different size extension's, an o2 sensor socket, flat head screw driver, Jack, jack stands, socket to remove wheels(I don't have facory wheels/lugs so I don't know what size most will need) torque wrench and I think that is about it.
Anyways on to the install and pics!
The pre-cats from RV6
I decided to paint them silver with some 2000 degree spray paint. The cat itself is made of stainless but was not sure about the rest so I added some protection from the elements with high temp paint. You can get them coated for another $80 and it takes another 2 weeks to get them as they have to be sent out to be coated.
First remove the engine cover.
Remove j-pipe. That is the RV6 J-pipe.
Removing o2 sensors and center spark plug coil. I only completely removed the top o2 sensors, the bottom sensors I removed from pre-cat and let them dangle at the bottom, removing all the little clips on those o2 sensors are a pain in the a** and can easily add another hr to the install.
Remove front pre-cat.
Install RV6 pre-cat and o2 sensors. Do not tighten pre-cat all the way yet, just leave it loose for now. Pic show it tightened all the way down but don't do that just yet.
Thats it for the front!
The rear goes about the same except for the actual removal of the pre-cat. Everything on the rear cat is done by laying over the top of the engine and doing it by feel rather than sight, makes it a bit more difficult but its not to bad.
Remove o2 sensors, remove all the nuts holding the pre-cat at the head, remove factory support bracket, remove pass side wheel, remove factory heat shield around pre-cat(wheel needs to come off first to get one of the bolts), remove guard around axle(sorry no pics of this item but you will see it when you are in there. The guard is held on by 3 bolts and it must be removed in order to get the pre-cat out.
Now you can slide the pre-cat out. This a bit tight but its really not bad. I would suggest putting something around your axle boot to keep from hitting or tearing it. Mine is actually already torn(you can probably see all the grease in some of the pics) so I did't really care about it. Its the next thing to get replaced but since I knew I was doing this I wanted to wait until the pre-cats where done so I did't have to risk tearing a new boot.
Both pre-cats are now removed. As you can see these are just as bad a design as the factory j-pipe is as far as flow goes. What you can't see is at the bottom of the rear cat(one without the shield) it has a big indention from the factory restricting flow even more.
Rear pre-cat being installed.
Rear Pre-cat lined up and loosly fitted.
Time to put the J-pipe back on.
Once the j-pipe is lined up you can tighten all the nuts at the j-pipe to the bottom flange of pre-cats, then tighten all the nuts at the pre-cat to head(remember we left them loose when we installed them earlier, this is why it makes it much easier to line up the j-pipe), then tighten the j-pipe to third cat. Then you can reinstall the fan and double check all your nuts bolts, wires, o2 sensors, and your done!
All that's left to do is take if for a test drive and get it good and warmed up, let it cool after the drive and recheck all your nuts and bolts to be sure they are good and tight.
Hopefully this will help anyone else looking to do this mod or anyone just looking to replace a faulty factory pre-cat. This really was not a bad job, like I said earlier it only took 3 hrs start to finish. I know I took more than 3 hrs last week to changing oil/filter, trans fluid, transfer fluid, brake fluid, power steering fluid, air filter, cabin filter.