[84CoupeGT]

I've just done this on mine (2.2, 5 cylinder), see latest post on my restoration thread. You don't need to remove anything to take the downpipe off (other than detach the rest of the exhaust from the downpipe). Obviously you need the front of the car raised up on stands or ramps. The 4 nuts which hold the downpipe to the manifold will likely be very rusty so spraying penetrating fluid on them for a few days before you tackle the job will likely help. The nuts are tricky to get to, I used a slim, long extension bar and needed a U-joint attachment at the far end for some of the nuts. When the nuts are off, you can withdraw the pipe but it does need to be "jiggled" in various directions on its way out. On mine, one of the studs broke off with the nut still rusted in position, so I had to buy a stud extractor socket to grip onto the stud and get it out. You can buy the studs new on eBay.

When reassembling, make sure you're not trying to get the downpipe back in the wrong route! I did this the first time (I was going up more vertically) - after a few minutes struggling I realised and felt very silly! Don't forget the washers and a new gasket. I used a silicone high temp sealant as well because the surfaces of the manifold and downpipe flanges were far from perfect even after lots of scraping/chiselling off the old gasket. I used traditional exhaust paste the first time which didn't work well and started blowing after a few months. I've not been able to start it since the latest installation but the silicon went on nicely and squeezed out a little around the joint (don't use too much though!), which has given me some confidence that the seal will be better this time.

Good luck, let us know how you get on!