Just thought I would write up my experience with installing the LG Street Series (with cats) in my 01 MN6 Coupe with 40K miles.

First, thanks to the install doc on LS1tech.com and the write-up by forum member CAJUNDUDE, everything went pretty much as expected. There were a few things that were not clear so maybe this will help someone.

I did everything in my garage with a pair of jack stands, Rhino ramps, and a floor jack. I did have a 3/8” air ratchet and that made things MUCH easier.

Removing the old system is pretty straight forward. I would recommend removing the alternator BEFORE removing the coil packs on the driver’s side. Makes getting that first bolt on the coil pack easier. Also, put the coil packs on first, then the alternator. I broke three OEM spark plug wires trying to get them off. They were replaced with MSD .. more on that later.

I also removed the heat shields on the old manifolds first .. made for a little more room to work. Also pulled the main hose out of the vacuum booster and pulled all the AIR tubes out of the way before trying to remove the manifolds. A 10mm ratchet wrench is your friend here.

The driver’s side header went up from the bottom no problem. The passenger side dropped in from the top. I found that I had to remove both the valve cover AND the starter from the passenger side. Some were able to get the header in without touching the starter, some have just loosened it. I decided to remove it completely. Made dropping the header in simple, and I was able to reach up and keep some wires out of the way with wire ties. If you go with this method, you have to reinstall the starter BEFORE bolting the header to the engine.

And now … the most important tip I can give .. it is VERY VERY easy to cross-thread the header bolts .. ask me how I know. You have to be super careful. Make sure you lift the header up and align it properly and start the header bolts BY HAND. You should be able to get 5-8 full turns by hand before meeting any real resistance. I did the install by myself and found it useful to stack some boxes under the car and rest the collector on the boxes, then carefully lower the car until the header is sitting in just about the right place. After the install, I found out about ARP header studs .. I would have gone with them had I known.

Make sure you get the F-body LS-1 gaskets instead of the Corvette gaskets. The openings are round instead of square and match up better to the headers.

Once the headers were in and loosely attached to the engine, it was time to go underneath. Some tips here … if you are running cats, you use the front O2 sensors WITH the extensions that come from LG and the back O2 sensors WITHOUT the extensions. It was freaking me out a little to have leftover parts. The front sensors are NOT crossed. The rear sensors ARE crossed. I added a coated stainless tunnel plate while everything was out. I did not drill any holes in the plate for the O2 sensor or wires. I used all the factory clips to route the wires around the pipes to the clips on the engine.

So, bolt up the cats to the collectors, then the mid-pipes to the cats. Tip here .. the O2 bungs mount closer to the cats. None of the docs I found were clear as to which way that pipe when in. Then I hung the back by one bolt on the springs and was able to start lining everything up and clamping.

Time to start bolting everything back together. No real surprises. I went with NGK TR55 copper plugs (gapped at .55), MSD 8.5mm wires and KoolSox. Don’t forget the dipstick!

The final step was to have the stock catback swapped for a Z06 Ti system. I took the car to a local muffler shop to do it as I was not comfortable with lifting the back end of the car three feet in the air. Also, the clamps that come from LG are not the best. I tightened them as much as possible but still had leaks. The muffler place removed all the clamps and TIG welded the entire system. I left the connection from the collector to the cats clamped in case I need to drop the system .. maybe for new heads. Total cost was $140.

Overall impressions are very good. The car pulls harder and smoother. Throttle response is better off idle. But the sound .. oh the sound .. is just wonderful. Quite at idle and cruising. No drone at all .. but screams at WOT.

Total time was about 16 hours stretched over 2 weekends (had to wait for wires and Koolsox from Thunder Racing). Total cost was around $2000. Smile when I put my foot down in 3rd gear … priceless.

Feel free to email me with any questions … rhubarb9999@gmail.com

 

Did mine in about 8 hours with a couple of buddies. Agree that clamps are less than optimal. Took me three tries over 3 months to solve. Found some really nice ones at Summit Racing. They stopped all the leaks.

Enjoy.

 

TorqTite stepped clamps...

 

Thanks for taking the time to submit such a good write up,

 

I'm gonna order the TorcTite clamps to replace mine for this same reason (keep getting a P0160 rear O2 sensor code for a cat-mid-tube section that leaks no matter what). What size clamp is it (I assume a 2-1/2 inch but wanted to make sure). Thanks.

 

For the LG Pros I did, that clamps were the 3" ones.

 

Awesome info. Especially about the clamps!! I have a set installed and have a leak and I am gettin codes. P1153H P1133H.

 

LG Street series should be 2 1/2 in. As mentioned, Pros are 3 in. No leaks on mine, yet, but I may have to get some of those clamps, anyway.