The three most common engine upgrades for an American V-twin are—hands down—high-flow air cleaner, a high-flow exhaust, and for the most power gains, a cam swap. Well this is exactly what we did with the 2018 Harley-Davidson Softail Street Bob equipped with the 107 Milwaukee-Eight engine. We used all parts from Screamin’ Eagle and racked up a total bill of approximately $1,450, including a tuner to reflash the ECU.
If you are looking for a nice bump in power with minimal effort, this would be a great setup for you. If you desire a little more, bumping up the displacement would be your next move. Running this setup, we went from 73.9 hp and 104.8 foot-pounds of torque to 92.4 hp and 106.3 foot-pounds of torque.
Screamin’ Eagle Milwaukee-Eight Stage II Torque Kit
The benefit to this kit with the adjustable pushrods is that they allow you to keep the rocker boxes intact, saving you time and money. This is possible by simply cutting out the old pushrods using a pair of bolt cutters. Another positive about this kit is that it retains its original-equipment factory warranty.
Screamin’ Eagle Street Cannon Mufflers, Long
The decibel rating is still within the legal limit, and these are all 50-state U.S. EPA compliant, so you won’t need to worry about ever getting a ticket because of your exhaust system. With a large 3.5-inch diameter, the Street Cannon mufflers offer a nice path for the exhaust gases to flow without compromising back pressure.
Screamin’ Eagle Extreme-Flow Air Cleaner; Round, Center Bolt
There are some stinkers out there, but most are going to do the intended job just fine. This essentially limits your decision to aesthetic. With the Extreme-Flow air cleaner, you get more of a naked, raw-power vibe. With no fancy cover, all you see is that filter. For the direction we went with the Street Bob, it fits perfectly. The Extreme-Flow from Screamin’ Eagle will cost you $199.95 from Harley-Davidson. The air cleaner is 50-state U.S. EPA compliant, and the kit includes all hardware needed for the installation.