Dented my headers to fit on my 69 camaro....?

I recently swapped my 355 sbc small block for a 454 big block and the hedman headers for the bbc didn't clear the steering box so I decided to bang the crap outta them. Now, they fit and clear everything.... my question is, since the headers weren't made espcially for a 69 camaro, would I lose any performance for the banged up header?? (I only had to bang one tube, not all 8.... Please let me know. Thanks!