Hi
Andy, my picture probably doesn't show how the two pieces connect. This might be clearer.
I found a 3" turbo downpipe on the bay of fleas. It was advertised to have a 2.5" outlet that would connect to the 2.5" Borla exhaust system I had already installed.
This seemingly simple pipe had four flaws: 1) it didn't have a catalytic converter, 2) it didn't have a post-cat O2 bung, 3) it wouldn't reach the 2.5" section of the exhaust pipe and 4) it had a 2.25" outlet.
The Borla exhaust is 2.5" except for the first few inches, which is swaged down to 2.25 inches. It also leaks so I'd like to have a better connection.
I bought a short high flow catalytic converter, a 3" to 2.5" stainless reducer and a stainless O2 bung. I then cut the pipe up.
The catalytic converter is a little longer than the piece I cut out so I trimmed it as much as I could. To get the extra length I wanted on the horizontal run, I spliced in the piece cut out for the cat.
Those band clamps are actually 3" alignment clamps with windows in the bands so you can tack the tubing.
I realized the exhaust system might hang lower than stock with my new downpipe. I wanted to fit it to the car. Because it's the only car my wife is comfortable driving, I don't want to do the final fitment until I have a few days to take it off the road.
One of these days...
I did some of the welding using my TIG but most was using my stainless MIG setup. I am trying to teach myself TIG because I haven't found any one-handed TIG instructions on YouTube. I've done some fusion and tried dipping rod but I foul the tungsten every time I take my eye off the arc and look to the filler rod.