Exhaust don't sound right

If you've got an O/R H-pipe, then you've still got the cross over. The cross over refers to the small section of exhaust pipe (usually 1-2 sizes smaller) that spans between each side of the mid pipe. It equalizes the exhaust pulses and aids in boosting low-end horsepower and torque.

The 5-inch long tips are not long enough to allow the exhaust tone to echo before exiting into the atmosphere. It's the same effect as if you were to yell into a toilet paper role (c'mon....you know you did it as a kid) and into a vacuum cleaner hose. The longer the section of tailpipe, the more it's going to resonate and echo after exiting the muffler, giving you the higher pitch throaty sound that you’re used to hearing with most Mustangs. Larger diameter exhaust pipe will deepen this tone, but going too large would hurt low-end torque.

If you’re planning to spring for another cat back system and want a little lower exhaust tone, and a tuned sound, go with a 2-½ inch (diameter) cat back with 3” (diameter) tips.

2-chamber Flowmasters are called 40-series
3-chamber Flowmasters are called 50-series

Yes, they do sell single chamber flows, but they’re loud and the noise will get tired fast. A 2-chamber set up with the above mentioned exhaust pipes should give you all the noise you’ll want.