I have only ridden it a couple of times and I still had the stock air cleaner on it. I seemed like it was running a little rich. There were a couple of pops occasionally when backing off. Nothing significant though. Overall, I really like it, so far. There is definitely a difference in power. The throttle response seems to be a little better also.
As far as the install, the pipes were easy and straight forward. The toughest part was removing the old pipes. I removed them a piece at a time and was wrapping them as I went, so they wouldn't get scratched. I followed the instructions to the letter for the installation of the new pipes and everything went without a hitch.
The install of the Fuelpak was also pretty simple. I did have to remove the ECM from the fender in order unhook the existing plug and install the new one. I tried to be creative on placement and fought it for a couple of evenings. The seat would not go back in place. I finally accepted my failure and used the diagram supplied by V&H. I was finally able to get it to fit, but there is zero extra space. I did have to relocate a small rectangular module from the front of the battery to an area a little forward of it's previous location.
I have now put on a Screaming Eagle heavy breather, but have not yet started it yet, so I can't rate final performance.