The 2018 Mustang 5.0 has a decent manifold setup in stock form, but you can wake it up with some long-tube headers. Whether catless or catted, there are gains to be made by swapping to long-tubes on either a naturally aspirated setup or a supercharged setup. Shorty headers are also available for any system that cannot have the elongated long-tube setup. Here at Lethal Performance we offer several high quality setups from manufacturers such as Kooks Custom Headers, American Racing Headers, Stainless Works/Stainless Power as well as some other budget friendly systems from Pypes, BBK Performance and JBA. For N/A setups a 1-3/4" header works great. If you're running forced induction though a 1-7/8" or 2" header will be better suited for that application. We ran a set of the American Racing Headers 1-7/8" headers along with their American Thunder catback on our 2015 GT that went 9.7@150. If you have any questions regarding a longtube header setup for your 2018 Mustang GT give your Lethal Performance sales associate a call today.