What do you guys think is happening with this Fiesta?

[uncleAl]

I am new to the forums here and have been wanting to buy a Fiesta ST for a while and may have found a good deal. Problem is, it's misfiring.

Oil looks good, has Cobb stage 3 tune, 112k miles, 2014, oil changed every 5k miles. Included a Youtube video link of it. Everything is pointing to a possible exhaust leak - when revved, it smells like exhaust in the engine bay. Not sure if this is a normal misfire sound on these. Any opinions would be great!

View: https://youtu.be/C3B0y38TGb0

 

[madhatter]

i'd wager it's a cracked exhaust manifold. Possibly cracked downpipe or a bad exhaust gasket, but i doubt it is a bad gasket.

that's definitely not a normal sound.