I got the 3.0L Downpipes w/HFC, ECU and TCU all at the same time on my '04 UltraSport with 45K miles. I am in NorCal so JHM did the install. I believe it was right around 9/13, so maybe a few days before the official release. As always, the work was completed when promised and the quality of the work is superb.
Pros:
I don’t race my Audi, so a few 10th’s in ET brackets doesn’t matter to me. What does matter is comfort and safety. I left the stock cat-back in place. I was concerned about drone with the DP’s coupled with aftermarket pipes. On another ride, my Hemi w shorties and custom cat-back let the engine breath and sounded bad-ass but on any drive longer than grocery-getting left me feeling like I wanted to strangle kittens. I may look into an aftermarket cat-back at some point in the future for the USP but for now there is absolutely zero drone with the stock cat-back. That is not to say that there is no difference in sound. Removing the tangled mess that passed for stock catalytic converters with the JHM downpipes definitely removed that “Constipated Duck” feeling and sound. The 3.Ohh is now more like a 3.Ahhhh. The tone is noticeably deeper at idle and under load it sounds more like a high performance German motor.
As for safety; I do a lot of driving between the Central Valley And Lake Tahoe. There are many places where 18 wheelers are driving around 30 MPH slower than I care to drive and if you can’t time passing them then you are stuck behind them. With the stock 3.0 the power band needed to make a decisive pass was unpredictable. With the DP’s and ECU the power comes on almost linearly and with consistency. Even charging uphill on a grade the motor delivers the power when requested and as long as it needed. And yeah,sometimes it just feels so good that before you realize it, you have passed with ease and are wondering how you got to 120 MPH.
The car has always been fun to drive and I do my share of spirited driving. I have noticed that even with a little more spirit than before I am still getting 2-3 more MPG on average since the tune.
Cons:
So far I haven’t had to smog the car since the tune. California is transitioning away from smog check tailpipe emissions testing to ODBII + visual inspections.
http://www.arb.ca.gov/msprog/smogcheck/march09/transitioning_to_obd_only_im.pdf
No more sniffer test where most aftermarket HFC’s would pass as long as the tester didn’t look at the cats for the CARB designation. Now, the testers will supposedly be required to do a visual inspection on every car. If I have to swap back to stock cats to pass smog that is going to be a major negative.
Other than that, there are no negatives for the downpipes or ECU.
I did mention that I also had the TCU tune done at the same time. If not for the TCU tuning, my wife wouldn’t have noticed anything. She took the car to the store one day. She didn’t notice the deeper tone of the exhaust. She did notice that the car got stuck in gear at around 30-40 MPH. She found it necessary to speed up, or slow down, to get it to change gears. Yeah, I have noticed the same thing. She also drove the Audi to Tahoe one day. I was already up there with the SUV and she was meeting me there. She pulled off of the highway and called me. The car according to her, “is broken.” At around 70-80 MPH, depending on the incline, the car constantly downshifts/upshifts repeatedly. I convinced her it wasn’t broken that it just needed an adjustment and she continued her drive. The vacillation between up and downshifts is annoying. Waiting to hear back on these issues.
If I were just using the car at the strip then the hard shifts would be fine. In my opinion it would be ideal if the TCU tuning could be restricted to Sport and Tip mode and revert to either a less aggressive or stock tune in Drive. Either that or be able to switch between Stock and Tuned mode for the TCU.