For what it's worth, I've seen dynos before and after of AA installing their headers, pulleys, and tune on an E46 M3. They gained about 30whp on a mustang dyno. Logical reasoning would say that the DKF exhaust is worth the power of AA's tune and pulleys since overall delta is the same. Of course, reality may say otherwise.
From what I hear, the AA headers don't produce as much power as SS Stepped, V2s, Agency Power, Evosport, etc. So I think it could be expected that the DKF system really works and adds some nice power!
