The Flowmaster 10 series will be a LOT louder and carry more rasp than the 40's. Just be aware of that before you make any purchases. I'm not saying it's a bad thing, but different customers have different opinions on exhaust, so just a heads up.
Unfortunately, we can't split up for Flowmaster 40 catback. It's delivered to us in a boxed package, so we're unable to alter them. However, we do carry the Flowmaster 10 series mufflers
separately and you could sell the 40's when they arrive.
On top of that, hit me up via PM if you haven't received the AM forum discount code, yet. It's for active users with 50+ posts to use as an appreciation for building the Mustang Community and the forum!
Almost forgot- You will need to weld some extra piping in to make the 10 series fit where the 40's once were. The 10 series is about half as long as the 40's, so you will come up short, unless extra pipe is welded in. This should be very simple for any exhaust shop though!