I ordered a Walker resonator/exhaust pipe, muffler, and gaskets etc. kit from RockAuto for my 2009 LS, but it hasn't arrived yet. Mine started with a noisier exhaust out of the muffler, but now has a leak somewhere around the driver's side rear wheel area. You can't tell from the diagram on RockAuto or other places (in email, Walker folks weren't sure either) whether the pipe comes with studs like the OE pipe. Has anyone had experience with this and does it come with studs? If so, what size nuts will I need? If it doesn't, what size bolts should I get? The Walker tech sent a diagram of the gasket; it has 1/2" diameter bolt holes. I'm considering 3/8" bolts, but what size will the OE cat flange accept? I'd appreciate any help because I'd rather gather everything together before I start the job. Thanks.

 

The OEM cat flange has studs. I can’t remember exactly what size, I think 8 mm .125 thread

 

Thanks, when I looked under there to spray them with Blaster, I found the studs are attached to the exhaust pipe and the nuts are on the cat side of that flange.

 

Then they are either 5/16 ths or 3/8’s bolts get flange bolts and nuts if possible.

 

Thanks, Blue, good idea on the flange bolts and nuts. Thanks, again.

 

Your welcome

 

Replaced my cat-back exhaust today; fortunately, a friend has a lift. I used Walker, and the fit was perfect. The studs are on the muffler side (smart on GM's part), so I used 3/8 x 1" flanged bolt and nut (but the metric equivalent because it was the only flanged they had, I think M10). Had to cut the nuts off because they were rusted away. I cut the old pipe near the two rear hanger arms to get it out. Drive-on lift, so maybe there would have been enough clearance if the axle was hanging down. It's a pretty easy job, but luckily, I didn't have to do it on jackstands.

 

Nice, a lift! I did that job on Oldblue, on jack stands, not a fun job , but not that bad with the rear axle down. A Sawzall helped!

 

I bought a cutoff tool at Harbor Freight, but then got a mandrel to hold the disk in my cordless drill. It worked OK, but the cutoff tool would have been quicker because of the higher speed. Returned the unused cutoff tool and saved myself $26. I originally expected to do it on jack stands, but glad I didn't have to.

 

It’s all installed now! You notice any thing with the 2 1/4 inch pipes?