For less than $100 and having at least two other uses I can already think of, it seemed like a safe bet.
I haven't used it under the car yet, but I did fire it up to see how it works and managed to pulverize a brick in about 5 seconds.
Update: I pounded one stud for 30 minutes and it didn't budge. About the only thing I haven't tried is putting a torch on it while running the air hammer.
I ended up using the stainless steel tie straps and they have been holding so far. The car is quiet--for now.