sorry to say it,im not a fan of flowmaster in the first place,but i can apreciate the guality of the original flowmasters, the thrush copys are nowhere close to the same quality, just need to look at the welds on most of them looks like they are even saving on the gas when welding, the V plate on the inside is not welded to the case in as many places either and they do come apart from time to time, and i would gues that they are even more restrictive compared to the originals. there is quite a diference betwen lower price and quality parts for half the price, as in most instances the old saying you get what you pay for holds true with these.
im not saying they are not a good sounding muffler cause they do sound pretty good and the quality is fair but whats the point in buying a fully welded muffler that is almost as sensitive to backfires as a normal muffler with rolled and pressed ends..