Since I wasn't involved in the earlier discussion, I'll put my $.02 in now. My boost response was improved (the turbos started spooling 3-4 hundred RPM sooner); on a more tired engine, I gained 6 more peak horsepower and a higher overall power curve; and the car ran about 1MPH faster in the 1/4 mile...these gains were over the first generation Dupree downpipes. YMMV. Take care, Mark