Just installed a downpipe on a 2012 hatch/lessons learned

I just completed the installation of an invidia catted dp on my 2012 WRX hatch and wanted to share what I found for others who do this. I'm by no means an expert in doing this sort of thing.
1. Have a friend help. I did it alone and was fine, but another set of hands would have helped in a couple of spots.
2. Make sure you get new gaskets (and an adapter if you are running a stock catback). I had already purchased a new doughnut gasket, but I've heard of people reusing them. Mine wasn't in any shape to be reused. They're pretty inexpensive anyway and its just the right thing to do.
3. Get the correct tools for the job. For the most part I was okay with box/crescent wrenches, ratchets, and a breaker bar. However, one of my turbo to dp bolts was hopeless and I ended up cutting it off. Luckily it was the topmost bolt, so I could get a dremel in there (with a right angle attachment and a cutting wheel). That part was a bitch. Later, the bolt holding the stock dp to that tab bracket under the car was rusted pretty good and couldn't be broken with a breaker bar. Luckily I borrowed a small air compressor and impact wrench from a neighbor. It still would not come off! I tried PB blaster and heat. Still no. Finally I heated it up even more than the first time and rocked the bolt back and forth (tighten then loosen) and it did break free. The impact wrench came in handy for the spring bolts to the catback as well, but they were less of an issue. I don't have any experience with electric impact wrenches, but I'd like to get one. Personally, I wouldn't have been able to get the old dp off without an impact wrench, so keep that in mind. My car has about 50,000 miles, so I can't imagine what one with 100k would be like if it was the first time the exhaust came off--at least with the NH winters.
Also, make sure to have extensions and u-joint adapters for ratchets and impact guns. Some of the spots are require some finagling to get a tool into.
I was perfectly fine using a large adjustable wrench (about 12" long) in place of an O2 sensor socket. It might be nice to have, but mine came off easily.

This install overall for me was moderately difficult--putting the new dp on was easy as pie, but getting the old one off wasn't--simply because of two bolts that needed some elbow grease, ingenuity, and proper tools. Some people recommend applying penetrating lubricant over the course of a few days before the installation, which I didn't do. However, even an overnight soak in PB Blaster didn't help that one bolt.

I'm currently running the Cobb stage 2+ sf 93 octane ots map, but will get a protune eventually. This is likely going to be my last performance mod for a while, unless I do a tgv delete, as I'd like to do a set of sways and endlinks and a bushing treatment, and possibly an AOS. I also really want to install an aftermarket turbo inlet too but looks like a tedious install.