Looks like a single chamber Flowmaster, but the muffler is actually a IMCO/Cherry Bomb single chamber muffler. Cherry Bomb is the consumer brand and more well known. That line's mufflers are painted red. IMCO is the non consumer line. They are non-stamped and a generic grey color. They were quite popular about a decade ago. The muffler has a similar sound to flowmasters but more aggressive.
Reason why I know those aren't Flowmasters are Flowmaster mufflers are always stamped.
How do they sound? I had them on a 2001 Mustang GT I owned over a decade ago. They sounded great. Flowmaster sound but more aggressive with less drone. Would have had them installed on my 2016 but all the videos I've heard of Flowmasters matched with a Coyote 5.0L, 1 and 2 chambers, have been very underwhelming for me and I came to the conclusion Flowmasters aren't a good match with Coyote.
I've had the IMCO single chambers on multiple vehicles over the years and would love to hear an exhaust video of them on an S550. Very throaty with lots and lots of pops and gurgles. They're only $50-75 a pair.
The IMCO single chamber mufflers are even more aggressive sounding than the Flowmaster single chamber (10-series)!
