Downpipe install writeup, pictures, tips, and links for FWD people (warning: long)

[RoninTT]

My flex bellow has been broken for the last couple of weeks so I decided to upgrade the downpipe on Saturday. I scored a very slightly used 2.5" Techtonics Tuning downpipe with high flow cat off of VWVortex. It took about 5.5 hours from start to finish. I don't have a lot of pictures but it's a pretty straightforward process. Remove old pipe, replace with new. I found this VW write-up very useful.

A look at the 95k miles old stock downpipe. I already have the o2 sensors unplugged. You want to leave them attached to the old pipe until it's out so they don't get damaged.

You can see half of the band clamp that had to be cut off the old exhaust on the right. I used a 4.5" angle grinder with a cutoff wheel to cut the clamp. You shouldn't need to cut the coupler that the clamp is wrapped around though, as the pipes should easily separate.
I removed the post-cat o2 sensor after the dp was off the car. The sensor had rusted into the dp pretty bad. I ended up heating it with a propane torch and spraying PB Blaster on it. After letting it sit for a few minutes, the sensor broke loose.

The dreaded turbo to downpipe flange nuts/studs.

You can see one of the studs and two of the nuts still threaded on. The most important part of all this is to remember to spray the 4 downpipe nuts with penetrating oil (NOT WD-40) before even attempting this. If one of the studs brakes off of the turbo you will be in a world of hurt. Luckily, it doesn't take much torque to remove the nuts IF you soak the crap out of them with PB Blaster. I jacked the car up Friday evening after driving around for about 20 minutes and doused the nuts with PB Blaster. Then, Saturday morning, I jacked it up again and doused the crap out of them once more. This time the engine was cold. I had read that you should do this while it's warm but I didn't feel like burning my hands and arms. I let them soak for about 30 minutes and they broke loose with no problems cold.

Heat shield removal...

There are 3 bolts and one nut holding this flimsy aluminum heat shield on. I had to remove it so I could get my arm up in there to get to the last dp nut. You may not have to do this if your arms are small. I would suggest not removing if you don't have to. It is a royal pain to get those bolts out. I don't know why VAG used such gigantic bolts for this thing but I only put one bolt and one nut back on it. It's not going anywhere.

Pic of me holding a deepwell 17mm socket and wrench.

This is the only nut that HAS to be dealt with from below. The other 3 can be gotten to from above with a box end wrench. You may not be able to see all 3 from above but trust me, they are a LOT easier to get to from up there. You just have to feel around for them a little. Also, having a ratcheting box-end wrench helps immensely.

Shot of new vs. old. New dp has o2 sensors installed.

The new one is discolored because I got it used.

Finishing up...
It took some finessing to get the new dp gasket to stay on while I lifted the new dp up onto the studs. Although I proved it can be done, I don't recommend doing this by yourself. Having someone up top to hold the gasket would've been nice.
If you elect to keep your stock exhaust, there will be a large (4" to 6") gap between the old pipe and the new dp. I'm not going to show a picture of my kludge of adapters, but suffice it to say, I will be getting a custom adapter made or upgrading to a full 2.5" exhaust in the future. I don't remember exacly but I think I used a 2.5" to 2.125" adapter coupled to the stock exhaust using the old "dp to exhaust" coupler and a 2.125" to 2.25" adapter. Not pretty.

Impressions:
The whole point was to fix the broken stock piece and it does that nicely. No more annoying exhaust vibrations when cold.

The manufacturer claims 10 to 15 hp gains and I can sorta feel a little more oomph in the midrange. If I had a full 2.5" exhaust or dump tube, and were chipped, I would expect this to give every bit of the claimed 10hp. The exhaust is not noticably louder but it does growl more when I floor it and the turbo hiss is a little more noticable now.

Notes:
-Before doing this, you will need to buy a new turbo->dp gasket, 4 new dp nuts and washers, and 4 new turbo studs (incase you break one). These parts should be no more than $10 total. Also, your life will be a lot easier if you have a set of ratcheting box-end wrenches (Gearwrenches).

-The cat heatsheild makes a nice resevior for whatever penetrating oil you choose to use. I got a face and neck full of PB Blaster when I started pulling the dp out. Nasty.

-Don't bother taking that damn aluminum heat shield off unless you really really need to. Those bolts are a pain.

-The new downpipe nuts the dealership sold me were 16mm, whereas the old nuts were 17mm. Not a pleasant surprise when the wrench slipped as I was tightening them.

-I didn't even bother with a torque wrench while tightening the dp nuts. There's no way to get one to fit up in there and using 20" of extensions with a u-joint isn't going to yield an accurate torque reading anyway. I torqued them to "tight enough".

[swishh]

[RedRoadster]

Eventually removing tha bottleneck of adapters and adding a catback will definitely help you, too.