Cobra PowrFlo 4-1/2" Slip-On Mufflers Chrome

In the case of your machine's configuration, if you haven't adjusted fuel delivery already, you'll certainly need to do that. A trip to the dyno is always best, but you'll need the requisite fuel tuning components to get the job done. For the amount of work you've had done, you'll need a TTS MasterTune Bike Communications Interface along with the TTS MasterTune Cable Kit to get the job done. Something like an Fi2000R or FP3 isn't going to be able to deliver enough fuel to get the job done. That said, if you've already had the engine tuning done, then you can probably get away with installing the slip-ons without issue since most of the exhaust restriction was removed with the OEM headers. Still, to get the best possible engine performance and throttle response, we always recommend that fuel delivery is updated any time you change the way air gets into, or out of, the engine.

Yes! If you were to choose the 2018 Harley Davidson FLHXS Street Glide Special PowerFlo slip-on muffler from our fit guide that's immediately to the right of the main image, you'd receive the correct parts to fit your machine.

All of the new intakes flow quite a bit more than the stock air filter. I would suggest the S&S stealth intake, you can run it with the factory cover with an adaptor plate or use one of their stylized skullcaps if you are after a custom look. The Vance and Hines FP3 is the easiest tuner to get installed and works flawlessly.

In most instances, on fuel-injected bikes at least, you won't need to adjust fuel delivery as the OEM ECU can handle those changes. Of course, this varies by machine. Now, if you have an aftermarket air cleaner on the bike in addition to the mufflers, then we advise would certainly advise adjusting fuel delivery to suit as the ECU doesn't have a proper map for that drastic of a change. If the latter describes your situation, we recommend a Cobra Fi2000R fuel tuner. The device is simple to install and adjust. And the included instructions provide excellent guidance on how to configure the device without the need to take a trip to a dyno tuner. Again, if you're just adding the slip-ons, there's no need to tune the bike. It's only when you go beyond those modifications that a tuner is required.