I you have a 600 cfm vac secondary carb, a 1500-6000rpm hi-rise dual-plane intake, something like a hi-energy cam, with of course your headers, expect a smile.
Also, let me add, that the length of the individual pipes on cheap T headers are not conducive for max power. The primary tubes are just too long, and with the (2) 90-degree bends. Don't get me wrong, they are alot better than logs....and look alot better. If you get the big tube headers that are equal length, (staggered up in the collector) they are tuned for max power, but they are not cheap.
Small primary pipes make for good low end, big ones male more top end. But, If you have long primarys, and you go big, you can still have great low end, the extra length is causing extra backpressure.