I like it, it sounds good, I even repurposed the sound for a Burnside engine I'm using, matches really well. It actually sounds different on the Burnside then the ETK's which is why it works(would not fit if it sounded like the it does with ETK's. It sounds more old-school muffled long-stroke V8 with the Burnside). Unfortunately ETK, or Burnside if suffers from the problem described below.
The Problem which is enough to take it down a star is the sound does not change when the exhaust is damaged, or without mufflers(I tested 4.5 V8 equipped ETK800 one with and one w/out exhaust they sounded same). It detracts from immersion/realism when the exhaust is off, or falls off, and the sound is the exact same.
As she is now I give the mod 4 of 5 due to the aforementioned exhaust problem.