hedman "tight tube" hedders?

So after reading this thread I went ahead and bought a set of uncoated Hedman Tight Tubes for my '70 Duster with a 360. I had them installed and the downpipes fab'd like on jerry6's ride. Unfortunately I wasn't crystal-clear with the exhaust guy on what I wanted done and he used the small reducers that came with the headers. They are already welded up and I owe $250 so it's too late to put bigger ones in. How much power will I lose compared to the biggest size I could run (2 1/4")?? My engine is .060"-over 1975 block with KB-107s, 10.6:1 comp, Lunati Voodoo 60401 cam, Magnum heads with 1.6 rockers, and Air-Gap intake.