I have put on the Mortons Down and out pipes and installed the Dobeck Techlusion controller for metric V- Twins. After putting on the pipes but before tuning the controller I was definitely running lean. With the controller properly set up the pipes are MUCH cooler and the bike pulls really hard. I don't know how much more air it lets it, but I have also drilled several holes on the back of the stock air box to allow more air into the engine. With the holes on the back I figure no rain should be able to be forced into the air box and the holes are small enough that no debris should be able to get in. There is definitely a good solid flow of cold air getting in and you can feel it when you are hard on the throttle. FUN!!!