I put a Starla exhaust system on my 1973 BMW 2002tii and the car developed an exhaust resonance between 3800 and 4300 rpm and later at around 3200 rpm.
The Starla was the suspect, since its muffler was a poor fit. The real culprit turned out to be a loose exhaust manifold stud which later backed out on 190. This was cured for less than $10, much less than it cost Mr. Simpkins (Roundel 5:2, p. 20), due to information in the Roundel.
BMWCCA has saved me many times the cost of membership. I suppose the stud was loosened up by the Starla system.
Author: Ted Burakoff
Possibly. The Starla system, made in Sweden, is the system that J.C. Whitney sells as its "economy" system for imported cars. Many people have had excellent results from the BMW OEM systems, made by either Eberspacher or by Leistritz. Tech Ed.