1-5/8 versus 1- 3/4 headers

This engine is not exactly all out, but it is fairly serious. It's a 11:1 360 with a set of mildly ported Edelbrocks, a mild hydraulic roller cam and a much modified LD 340 manifold and a big TQ. I have so much bottom end at the moment that I have a lot of traction problems, so i certainly don't need any more. My main concern is losing out on the mid range onwards from the smaller primary pipes on the headers.
Thanks for your replies