I installed the IPD Downpipe in my 2004 V70R today. The job, while time consuming, actually went more smoothly than I expected. All of the turbo nuts as well as the exhaust flange nuts came off like the car was built yesterday. I guess that would be a tribute to PB Blaster and car friendly southern weather. I gave the nuts a dose of PB Blaster a couple weeks ago and then again when I started the job.
The rear O2 sensor was a bit stubborn and I ended up disconnecting it and removing it once the downpipe was out of the car. At that point I had it out in 5 minutes with some more PB Blaster and tapping the O2 sensor tool handle with a hammer a bit.
What took the time was stupid stuff. It took me a while to figure out how to disconnect that rear O2 sensor. I finally realized that I could use the O2 sensor extension cable that IPD provided as an example to figure out how the latch worked. Even so it was a bit stubborn to release and needed some convincing with the tip of a flat screwdriver. It's in a really bad spot too. I ended up removing the driver's side front wheel to gain better access from the side.
The other time waster was the rubber hangers that support the down pipe. I didn't have a puller and had to struggle forever with screwdrivers to get the the hanger off the old downpipe and later onto the new one.
Other than that the install was straightforward. The new downpipe is quite a bit bigger and clearances in some spots are very tight at 1/8" or so. But so far I don't hear any rattles or vibrations.
The quality of the IPD downpipe is excellent. Everything fit and it even had the arm that supports the O2 sensor cable clamp. It would have been nice if IPD made some attempt at some install documentation. Nothing was provided at all and it would have been a nice touch and probably saved a boat load of time.
With the new downpipe I don't notice any obtrusive exhaust sounds. The exhaust level is perfectly fine. It might be a bit louder when you get on it. I do hear the turbo spooling up quite a bit more. It sounds like ""WoShhhhhhhhhhh". It has me wondering if there is a leak somewhere, although the sound is more like air rushing than any type of exhaust leak I've ever heard.
As far as performance goes, the car seems to develop power much more quickly. It also seems to develop power with less throttle input. I like it so far. Too soon to say anything about fuel economy.