I installed my BigFlow 1 7/8 LTs with high flow cats on my LS3 yesterday.
Mostly everything wet smoothly. I started this install by watching a video and reading every thread I could find on the topic. Everyone should start here:
After looking through the list and later reading about broken spark plugs I decided to take mine out.
There are two problem areas: O2 removal and Oil dipstick replacement.
As for the O2s I ran my car for a few moments and then drove up on the ramps and then sprayed all the sensors. The key is I think is run the car long enough to get the exhaust warm, but not long enough for the heat to travel up to the O2 sensor. Then I used my O2 removal socket. I have removed O2 sensors before, these things make the job easy and helps prevent i think O2 damage.
As to Dipstick replacement I placed tap on the valve cover where the dipstick end comes up by the top of the engine and where the dipstick bends down. Then before I removed the dip stick I felt under the starter where the dipstick enters the pan. This prep with a friend feeding the dipstick down made replacement a 2 minute job.
PlanetLSX says the car must be at least 2 feet off the ground. Way over kill. I did my install with 10 inch high ramps. the only problem I had was removing the drivers side manifold and cats. I jacked up the car another 4 inches and the ugly thing slid right out. I also heard that one guy removed the cats from the manifolds and installed LTs with less than 10 inches of lift.
One PIA was the O2 Plugs. They have these little pins you have to pull out that you do not need to put back in later. The 2 rear ones pull out with a pair of pliers. But the 2 in the back of the cylinder heads have these little plastic strings you can use to pull the pins out. You would never be able to put these back in. The clips hold the plug in just fine. Plug the front O2 sensors back in from under the car. My LTs needed the plug extensions.
The rest of the install went smoothly except for one thing but took all day until the night. Many say it could be done in two hours. Not by me at least. I did have a friend helping me by taking out a few bolts, and assisting with the dipstick replacement, and initial header positioning.
I am not voiding my warranty by tuning my car just yet. So I installed rear O2 spacers to help prevent the dreaded CELs. No CELs so far after one day.
After all my preparation and taking my time I was shocked when after installing the tubes I realized my cats were not going to fit. I was told by the people who sold me the long tubes that they would bolt right up to my stock cutback. Not so, they are three inches too long!
I was not sure what to do next. Put everything back together and the manifolds back in? Leave the car on the ramps and see if I could find shorter cats? My friend said he had a sawmill. I decided ti bit the bullet and cut. I tightened down the headers for position and carefully measured and then bravely took a big saw to my car. It turned out there was just barely enough room to fit the cats before the first bend in the pipe. But I did get it to fit.
One last thing. The passenger side has very little room to work. You just need to be patient and keep trying different extensions and combinations. I used my 1/2 and 3/8 socket sets. Why are the manifold bolts 1/2 inch standard? Because I everything is so tight I tore up the insulation on the firewall removing those back bolts. Why is the insulation so flimsy? I also tore up the back of my hands.
The big cut was from my pit bull. I opened that up a few times during the install. She is a little too excitable sometimes.
So at 9 PM I took the car out for the first time with the LTs. I was exciting. Since I am using the stock catback it sound almost stock most of the time. But wan you ht 4-5 K it starts to wail. The sound is a ripping sound sort of high pitched and loud. The car now has sort of a Jekyll and Hyde character. I enjoy cruising and I like the quiet side of the car for that. and I really hate drone. The car has none.
I definitely feel more power. Now when I open it up in first gear the traction control light is on until I hit second. Fun! I plan to keep cloves of garlic on the rear view mirror to keep away the CELs. Wish me luck.
Edit: One CEL so far. Nothing to be afraid of.